Method and apparatus for transmitting/receiving positioning reference signal

ABSTRACT

An apparatus and method for processing positioning reference signal are disclosed. A method may include receiving, by a narrow-band (NB) user equipment (UE), positioning reference signal (PRS) configuration information, determining, by the NB UE, narrowband PRS (NB PRS) configuration information for the NB UE, the NB PRS configuration information comprising information of an NB PRS reference cell that generates an NB PRS for the NB UE, determining, by the NB UE, PRS configuration information for a UE, the UE being assigned to use a frequency band unavailable for the NB UE, and the PRS configuration information comprising information of a PRS reference cell that generates a PRS for the UE, generating, based on the NB PRS configuration information and the PRS configuration information, a reference signal time difference (RSTD) measurement, and transmitting, by the NB UE, the RSTD measurement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/673,840, filed on Aug. 10, 2017, which claims priority from and thebenefit of Korean Patent Application Nos. 10-2016-0103209, filed on Aug.12, 2016, and 10-2016-0126856, filed on Sep. 30, 2016, which are herebyincorporated by reference in their entirety.

BACKGROUND 1. Field

The present disclosure relates to a wireless communication system, andmore particularly, to a method and apparatus for transmitting orreceiving a positioning reference signal for a Narrowband Internet ofThings device.

2. Discussion of the Background

The Narrowband Internet of Things (NB-IoT) concept has been proposed forthe purpose of radio access to the cellular IoT based on anon-backward-compatible variant of Evolved-Universal Terrestrial RadioAccess (E-UTRA).

The NB-IoT may improve indoor coverage, and may support a large numberof low throughput devices, low delay sensitivity, a significantly lowdevice cost than that of smartphones, low device power consumption, andan optimized network architecture.

The NB-IoT uses a narrow band (e.g. a bandwidth corresponding to asingle Resource Block (RB) or the like), and thus physical channels,signals, and the like which have been utilized in E-UTRA, such as legacyLong-Term Evolution (LTE), may need to be newly designed. There is aneed for a method of configuring a resource for a Positioning ReferenceSignal (PRS) to be appropriate for a narrow bandwidth, and mapping thesequence of such a PRS to the allocated resource.

However, a detailed method for configuring a PRS for NB-IoT has not yetbeen determined.

SUMMARY

A method and apparatus for supporting positioning in an NB-IoT systemwill be described.

One or more examples describe an operation method and apparatus forperforming positioning for NB-IoT based on both a PRS for LTE and a PRSfor NB-IoT.

One or more examples describe a method and apparatus for transmitting aPRS for NB-IoT for securing extreme coverage.

One or more examples describe a user equipment (UE) operation method andapparatus in a configuration in which an NB channel, signal, orconfiguration overlaps a transmission subframe of a PRS for NB-IoT.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the configuration of a wireless device.

FIGS. 2 and 3 are diagrams illustrating the structure of a radio frameof a 3GPP LTE system.

FIG. 4 is a diagram illustrating the structure of a downlink subframe.

FIG. 5 is a diagram illustrating the structure of an uplink subframe.

FIG. 6 is a diagram illustrating an example of NB-IoT.

FIGS. 7A-7C are diagrams illustrating an NB-IoT operation mode.

FIG. 8 is a diagram illustrating a resource allocation scheme for anNB-IoT signal and a legacy LTE signal in an in-band operation mode.

FIG. 9 is a diagram illustrating an NPBCH transmission scheme in anin-band operation mode.

FIG. 10 is a diagram illustrating a Narrowband Control Channel Element(NCCE) resource allocation scheme in an in-band operation mode.

FIG. 11 is a diagram illustrating rate matching associated with atransport block and cyclic subframe level repetition.

FIGS. 12 and 13 are diagrams illustrating an RE pattern in which an LTEPRS is mapped to a single resource block pair.

FIG. 14 is a diagram illustrating an Observed Time Difference Of Arrival(OTDOA) process.

FIG. 15 is a diagram illustrating a control plane and a user plane of anLTE positioning protocol (LPP).

FIG. 16 is a diagram illustrating an example of a first PRS transmissionresource and a second PRS transmission resource.

FIGS. 17A, 17B, 18A, 18B, 19A, 19B, and 20 are diagrams illustrating anNB-PRS RE mapping pattern in a guard-band or a standalone operationmode.

FIGS. 21 and 22 are diagrams illustrating other examples of a first PRStransmission resource and a second PRS transmission resource.

FIGS. 23-25 are diagrams illustrating examples of configuring an NB-PRSoccasion.

FIG. 26 is a diagram illustrating a valid subframe for an NB-PRS.

FIG. 27 is a diagram illustrating an NB-PRS transmission operation whenan NB-PRS transmission subframe overlaps an NPDCCH transmissionsubframe.

FIG. 28 is a diagram illustrating an NB-PRS subframe that overlaps an NBchannel and a downlink gap.

FIG. 29 is a flowchart illustrating NB-PRS transmission and receptionoperations.

FIG. 30 is a diagram illustrating the configuration of a process of awireless device.

DETAILED DESCRIPTION

Various examples will be described more fully hereinafter with referenceto the accompanying drawings. Throughout the drawings and the detaileddescription, unless otherwise described, the same drawing referencenumerals are understood to refer to the same elements, features, andstructures. In the present disclosure, detailed descriptions of knownconfigurations or functions may be omitted for clarity and conciseness.

Further, the description herein is related to a wireless communicationnetwork, and an operation performed in a wireless communication networkmay be performed in a process of controlling a network and transmittingdata by a system that controls a wireless network (e.g., a basestation), or may be performed in a user equipment connected to thewireless communication network.

That is, it is apparent that various operations, which are performed forcommunicating with a terminal in a network of a plurality of nodesincluding a base station (BS), are executable by the BS or by othernetwork nodes excluding the BS. The ‘BS’ may be replaced with terms suchas a fixed station, a Node B, an evolved Node B (eNB), an access point(AP), and the like. Also, ‘terminal’ may be replaced with terms such asa User Equipment (UE), a Mobile Station (MS), a Mobile SubscriberStation (MSS), a Subscriber Station (SS), a non-AP station (non-AP STA),and the like.

Various examples have been described with respect to 3GPP LTE or LTE-Asystems; however, aspects of the present disclosure may be applied toother mobile communication systems.

FIG. 1 is a diagram illustrating the configuration of a wireless device.

FIG. 1 illustrates a UE 100 that corresponds to an example of a downlinkreceiving device or an uplink transmitting device, and an eNB 200 thatcorresponds to an example of a downlink transmitting device or an uplinkreceiving device. Although not illustrated in FIG. 1, another UE thatperforms V2X communication with the UE 100 may exist. The configurationof the other UE is similar to that of the UE 100, and thus detaileddescriptions thereof will be omitted.

The UE 100 may include a processor 110, an antenna unit 120, atransceiver 130, and a memory 140.

The processor 110 may process signals related to a baseband, and mayinclude a higher layer processing unit 111 and a physical layerprocessing unit 112. The higher layer processing unit 111 may processthe operations of a Medium Access Control (MAC) layer, a Radio ResourceControl (RRC) layer, or a higher layer. The physical layer processingunit 112 may process the operations of a PHY layer (e.g., processing anuplink transmission signal or processing a downlink reception signal).The processor 110 may control the general operations of the UE 100, inaddition to processing signals related to a baseband.

The antenna unit 120 may include one or more physical antennas, and maysupport MIMO transmission/reception when a plurality of antennas areincluded. The transceiver 130 may include a Radio Frequency (RF)transmitter and an RF receiver. The memory 140 may store informationprocessed by the processor 110, software, an operating system,applications, or the like associated with the operations of the UE 100,and may include elements such as a buffer or the like.

The eNB 200 may include a processor 210, an antenna unit 220, atransceiver 230, and a memory 240.

The processor 210 processes signals related to a baseband, and mayinclude a higher layer processing unit 211 and a physical layerprocessing unit 212. The higher layer processing unit 211 may processthe operations of an MAC layer, an RRC layer, or a higher layer. Thephysical layer processing unit 212 may process the operations of a PHYlayer (e.g., processing a downlink transmission signal or an uplinkreception signal). The processor 210 may control the general operationsof the eNB 200, in addition to processing signals related to a baseband.

The antenna unit 220 may include one or more physical antennas, and maysupport MIMO transmission/reception when a plurality of antennas areincluded. The transceiver 230 may include an RF transmitter and an RFreceiver. The memory 240 may store information processed by theprocessor 210, software, an operating system, applications, or the likeassociated with the operations of the eNB 200, and may include elementssuch as a buffer or the like.

The processor 110 of the UE 100 may be configured to implement theoperations of the UE, which are described herein.

An example of a radio frame structure will be described below.

FIGS. 2 and 3 are diagrams illustrating the structure of a radio frameof a 3GPP LTE system.

In a cellular wireless packet communication system, uplink transmissionor downlink transmission is executed in units of subframes. A singlesubframe is defined as a predetermined period of time including aplurality of symbols. The 3GPP LTE standard supports the radio framestructure type 1 that is applied to Frequency Division Duplex (FDD) andthe radio frame structure type 2 that is applied to Time Division Duplex(TDD).

FIG. 2 illustrates the radio frame structure type 1. A single radioframe is formed of 10 subframes, and a single subframe is formed of 2slots in the time domain. A time expended for transmitting a singlesubframe is a Transmission Time Interval (TTI). For example, the lengthof a single subframe is 1 ms, and the length of a single slot is 0.5 ms.A single slot may include a plurality of symbols in the time domain. Thesymbol may be an Orthogonal Frequency Division Multiplexing (OFDM)symbol in the downlink, or may be a Single Carrier-Frequency DivisionMultiple Access (SC-FDMA) in the uplink, but the symbol may not belimited thereto. The number of symbols included in a single slot may bedifferent based on the Cyclic Prefix (CP) configuration. The CP mayinclude an extended CP and a normal CP. In the case of the normal CP,for example, the number of symbols included in a single slot may be 7.In the case of the extended CP, the length of a symbol is extended andthus, the number of symbols included in a single slot may be 6, which issmaller than the normal CP. When the size of a cell is large or when achannel state is unstable, such as when a User Equipment (UE) movesquickly or the like, an extended CP may be used to reduce inter-symbolinterference.

In FIG. 2, by assuming the case of the normal CP in a resource grid, asingle slot corresponds to 7 symbols in the time domain. In thefrequency domain, a system bandwidth is defined to be an integer (N)multiplied by a Resource Block (RB), a downlink system bandwidth may beindicated by a parameter N^(DL), and an uplink system bandwidth may beindicated by a parameter N^(UL). A resource block is a resourceallocation unit, and may correspond to a plurality of symbols (e.g., 7symbols) occupying a single slot in the time domain and a plurality ofconsecutive subcarriers (e.g., 12 subcarriers) in the frequency domain.Each element in a resource grid is referred to as a Resource Element(RE). A single resource block includes 12×7 REs. The resource grid inFIG. 2 may be applied equally to an uplink slot and a downlink slot.Also, the resource grid in FIG. 2 may be equally applied to a slot ofthe radio frame structure type 1 and a slot of the radio frame structuretype 2, the latter of which will be described as follows.

FIG. 3 illustrates the radio frame structure type 2. The radio framestructure type 2 is formed of 2 half frames, and each half frame may beformed of 5 subframes, a Downlink Pilot Time Slot (DwPTS), a GuardPeriod (GP), and an Uplink Pilot Time Slot (UpPTS). Like the radio framestructure type 1, a single subframe is formed of 2 slots. The DwPTS isused in a UE for initial cell search, synchronization, or channelestimation, in addition to transmission/reception of data. The UpPTS isused in an eNB for channel estimation and the UE's uplink transmissionsynchronization. The GP is the period between an uplink and a downlinkfor removing interference generated in the uplink due to a multi-pathdelay of a downlink signal. The DwPTS, GP, and UpPTS may be alsoreferred to as special subframes.

FIG. 4 is a diagram illustrating the structure of a downlink subframe. Aplurality of OFDM symbols (e.g., 3 OFDM symbols) in the front part of afirst slot in a single subframe may correspond to a control region towhich a control channel is allocated. The remaining OFDM symbolscorrespond to a data region to which a Physical Downlink Shared Channel(PDSCH) is allocated. Downlink control channels used in the 3GPP LTEsystem may include a Physical Control Format Indicator Channel (PCFICH),a Physical Downlink Control Channel (PDCCH), a Physical Hybrid automaticrepeat request Indicator Channel (PHICH), and the like. In addition, anEnhanced Physical Downlink Control Channel (EPDCCH) may be transmittedto UEs set by an eNB in the data region.

The PCFICH is transmitted in the first OFDM symbol of a subframe, andmay include information associated with the number of OFDM symbols usedfor a control channel transmission in the subframe.

The PHICH is a response to an uplink transmission, and includes HARQ-ACKinformation.

Control information transmitted through the (E)PDCCH is referred to asdownlink control information (DCI). The DCI includes uplink or downlinkscheduling information, or may include other control information basedon various purposes, such as a command for controlling uplinktransmission power with respect to a UE group or the like. An eNBdetermines an (E)PDCCH format based on DCI transmitted to a UE, andassigns a Cyclic Redundancy Check (CRC) to control information. The CRCis masked with a Radio Network Temporary Identifier (RNTI) selectedbased on a use type or a transmitting entity of the (E)PDCCH. When the(E)PDCCH is used for a predetermined UE, the CRC may be masked with acell-RNTI (C-RNTI) of the UE. Alternatively, when the (E)PDCCH is usedfor a paging message, the CRC may be masked with a paging indicatoridentifier (P-RNTI). When the (E)PDCCH is used for a system informationblock (SIB), the CRC may be masked with a system information identifierand a system information RNTI (SI-RNTI). To indicate a random accessresponse with respect to a random access preamble transmission of a UE,the CRC may be masked with a random access-RNTI (RA-RNTI).

FIG. 5 is a diagram illustrating the structure of an uplink subframe. Anuplink subframe may be divided into a control region and a data regionin the frequency domain. A physical uplink control channel (PUCCH)including uplink control information may be allocated to the controlregion. A physical uplink shared channel (PUSCH) including user data maybe allocated to the data region. A PUCCH for a single terminal may beallocated to a resource block pair (RB pair) in a subframe. The resourceblocks included in the RB pair may occupy different sub-carriers withrespect to two slots, which indicates that the RB pair allocated to aPUCCH is frequency-hopped at a slot boundary.

FIG. 6 is a diagram illustrating an example of NB-IoT.

From the perspective of Internet of Things (IoT) technology, NB-IoT maybe connected to the basic concept of Machine-Type Communication (MTC) orMachine to Machine (M2M) communication, except for the fact that NB-IoTuses a narrow band. NB-IoT may include the exchange of informationbetween NB-IoT UEs 11 and 12 through an eNB 15, excluding humaninteraction, or alternatively may include the exchange of informationbetween the NB-IoT UE 11 and 12 and an NB-IoT server 18 through an eNB.

The NB-IoT server 18 may be an entity that communicates with the NB-IoTUEs 11 and 12. The NB-IoT server may execute an NB-IoT-relatedapplication, and may provide an NB-IoT-specific service to the NB-IoTUEs 11 and 12.

The NB-IoT UEs 11 and 12 may be stationary or mobile wireless devicesthat provide NB-IoT.

FIGS. 7A-7C are diagrams illustrating an NB-IoT operation mode.

NB-IoTs may operate in one of three operation modes as shown in FIG. 7.The three operation modes are a standalone operation mode, a guard-bandoperation mode, and an in-band operation mode.

FIG. 7A illustrates a standalone operation mode. A spectrum currentlyused in an Enhanced Data Rates for GSM Evolution (GSM/EDGE) Radio AccessNetwork (GERAN) system, which corresponds to one or more Global Systemfor Mobile Communications (GSM) carriers, may be used. For example, oneof the GSM carriers (e.g., a frequency region of a 200 kHz-bandwidth)may be used for NB-IoT technology.

FIG. 7B illustrates a guard-band operation mode. Resource blocks, whichare not used in a guard-band existing outside the bandwidth of an LTEcarrier, may be used.

FIG. 7C illustrates an in-band operation mode. Resource blocks in thebandwidth of an LTE carrier may be used. For example, one PRB in the LTEbandwidth (e.g., a frequency region of a 180 kHz-bandwidth) may be usedfor NB-IoT.

NB-IoT devices aim to mainly support scenarios in which NB-IoT devicesare operated in buildings or basements of buildings in order to providea smart metering service, a smart home service, an alarm service, or thelike. This may mean that reliable data transmission/reception needs tobe supported in rooms or basements that are generally known to be lowperformance areas, irrespective of the deployment of NB-IoT devices.Further, lower power consumption and less complexity need to bemaintained, and at the same time, connections to multiple NB-IoT devices(50,000 NB-IoT devices from the perspective of a single cell) need to bemaintained. The requirements of an NB-IoT system, considered here on thebasis of the technologies associated with the GERAN system, are as shownin Table 1.

TABLE 1 Performance Objectives Improved indoor MCL (Maximum CouplingLoss) 164 dB coverage Cell Capacity 52574 devices per cell Reduced Verycheap based on mass scale deployment complexity or in a disposablemanner Improved power About 10-year battery life efficiency Latency 10seconds for Mobile Autonomous Reporting (MAR) exception reports (ingeneral support relaxed delay characteristics Coexistence GSM/WCDMA/LTE

The characteristics of a downlink defined in the NB-IoT will bedescribed here. An NB-IoT downlink has a subcarrier spacing of 15 kHz,as in conventional LTE, and has a resource structure defined by a 180kHz band corresponding to a single Physical Resource Block (PRB) in thefrequency axis and by a Transmission Time Interval (TTI) of 1 mscorresponding to a single subframe and a radio frame of 10 ms in thetime axis. As described above, because NB-IoT operates a service in anin-band operation mode or a guard-band operation mode on a carrier whereLTE operates, NB-IoT is designed to adopt LTE numerology that defines aphysical layer structure, as those of LTE, in order to avoidinterference with LTE.

A Narrowband Primary Synchronization Signal (NPSS) and a NarrowbandSecondary Synchronization Signal (NSSS), which are synchronizationsignals in the NB-IoT, may have different characteristics from asynchronization signal in conventional LTE. The NPSS includes aZadoff-Chu (ZC) sequence having a sequence length of 11 and a root indexvalue of 5. The NSSS includes a combination of a ZC sequence having asequence length of 131 and a binary scrambling sequence, such as aHadamard sequence. In particular, the NSSS indicates a Physical CellIdentity (PCID) to NB-IoT UEs in a cell through a combination of thesequences. Also, in order to reduce the number of times that blinddecoding is performed during the reception of a Narrowband PhysicalBroadcasting Channel (NPBCH) that transfers Master Information Block(MIB) information in a NB-IoT system, four NSSS transmission frames areindicated to correspond to four cyclic shift values forming an NSSSsequence within a 80 ms-frame.

FIG. 8 is a diagram illustrating a resource allocation scheme for anNB-IoT signal and a legacy LTE signal in an in-band operation mode. Forease of implementation, an NPSS and an NSSS are not transmitted in firstthree OFDM symbols of a subframe corresponding to a transmissionresource region for a control channel in conventional LTE, irrespectiveof operation mode. Resource Elements (REs) for an NPSS/NSSS thatcollides with a Common Reference Signal (CRS) of conventional LTE on aphysical resource are punctured, thereby not affecting a legacy LTEsystem.

FIG. 9 is a diagram illustrating an NPBCH transmission scheme in anin-band operation mode.

An NPBCH (or NB-PBCH) is transmitted in a subframe having a subframeindex value of 0 in each radio frame. In the subframe in which an NPBCHis transmitted, the first three OFDM symbols are not used fortransmitting an NPBCH, irrespective of NB-IoT operation mode. An NPBCHrecognizes resource allocation information associated with an RE usedfor a CRS in LTE based on a Physical Cell Identity (PCID) obtained froman NSSS, and performs rate matching accordingly. The same MIBinformation transmitted through an NPBCH is maintained during 640 ms,and is configured as an information block that may be independentlydecoded during 80 ms, as shown in FIG. 9. Through the above describedtransmission scheme, an NB-IoT UE may more reliably decode an NPBCH andmay provide a lower access delay speed. Also, MIB information mayinclude a system frame number, HyperSFN (i.e., index information thatincreases for each SFN wrap-around), a system information value tag, thenumber of LTE CRS antenna ports, the operation mode, a channel rasteroffset, SIB1 scheduling information, and the like, which are importantinformation that a UE needs in order to access an NB-IoT system. The MIBinformation may be provided to NB-IoT UEs in a cell.

FIG. 10 is a diagram illustrating a Narrowband Control Channel Element(NCCE) resource allocation scheme in an in-band operation mode.

The characteristics of a physical layer associated with a NarrowbandPhysical Downlink Shared Channel (NPDSCH) for transmitting data and witha Narrowband Physical Downlink Control Channel (NPDCCH) for transmittingcontrol information and scheduling information for data in an NB-IoTsystem will be described as follows. In the case of an NPDCCH, aNarrowband Control Channel Element (NCCE) is configured without defininga Resource Element Group (REG), unlike a Physical Downlink ControlChannel and an Enhanced PDCCH (EPDCCH), which comprise a plurality ofREGs. Further, two NCCEs are allocated to a single PRB pair, as shown inFIG. 10. Therefore, a minimum resource unit forming an NPDCCH is anNCCE. NPDCCH format 1, which includes a maximum of 2 NCCEs (whereasNPDCCH format 0 includes a single NCCE), may be repeatedly transmittedin a plurality of subframes in order to provide wider-than-normalcoverage.

Therefore, a UE needs to know in advance information associated with asearch space for decoding an NPDCCH, which may be transmitted in asingle or a plurality of subframes. The search space for an NPDCCHincludes both a UE-specific search space for a UE's unicast datascheduling and a common search space for paging and random access, likea PDCCH in conventional LTE.

From the perspective of a UE-specific search space, a UE performs blinddecoding of a plurality of NPDCCH candidate transmissions determinedaccording to a repetition level (R) and a concatenation level (L′ϵ{1,2})on the basis of the maximum repetition level (R_(max)), in a searchspace start subframe indicated by higher layer signaling as shown inTable 2. The UE may obtain scheduling information for the reception ofan NPDSCH by receiving an NPDCCH. NPDCCH format 1 and NPDCCH format 2,which are Downlink Control Information (DCI) formats in NB-IoT, mayindicate a scheduling delay for the timing of an NPDSCH transmissionsubframe.

Table 2 indicates NPDCCH UE-specific search space candidates.

TABLE 2 NCCE indices of monitored NPDCCH candidates R_(max) R L′ = 1 L′= 2 1 1 {0}, {1} {0, 1} 2 1 {0}, {1} {0, 1} 2 — {0, 1} 4 1 — {0, 1} 2 —{0, 1} 4 — {0, 1} >=8 R_(max)/8 — {0, 1} R_(max)/4 — {0, 1} R_(max)/2 —{0, 1} R_(max) — {0, 1} Note 1: {x}, {y} denotes NPDCCH Format 0candidate with NCCE index ‘x’, and NPDCCH Format 0 candidate with NCCEindex ‘y’ are monitored Note 2: {x, y} denotes NPDCCH Format1 candidatecorresponding to NCCEs ‘x’ and ‘y’ is monitored.

FIG. 11 is a diagram illustrating rate matching associated with atransport block and cyclic subframe level repetition.

An NPDSCH may transmit a Transport Block (TB) having a Transport BlockSize (TBS) of a maximum of 680 bits through one or more PRB pairs. Thepossible range of the quantity of PRB pairs may be one to a maximum often PRB pairs. A single TB is cyclically and repeatedly transmitted in aplurality of subframes. For example, rate matching associated with asingle TB is performed, whereby the single TB is cyclically andrepeatedly transmitted in a plurality of subframes through an NPDSCH, asshown in FIG. 11. The cyclic repetitive transmission may also be appliedto a Narrowband Physical Uplink Shared Channel (NPUSCH), which is anuplink data channel.

In addition, a gap may be configured for uplink and/or downlink betweencontinuous repetitive transmissions of a large number of physicalchannels, in order to secure the transmission of control information anddata for other UEs.

Next, operations of a system in which different Positioning ReferenceSignals (PRS) are defined will be described. The different PRSs may bereferred to as a first PRS and a second PRS. For example, the first PRSmay be a PRS used in NB-IoT (hereinafter an NB-PRS), and the second PRSmay be a PRS defined in an LTE system (hereinafter LTE PRS). Althoughthe following examples are described by assuming that the first PRS isan NB-PRS and the second PRS is an LTE PRS, examples are not limitedthereto, and the following examples may be applied when different PRSsare defined.

Before the description of examples associated with an NB-PRS, an LTE PRSwill be described.

An LTE PRS may only be transmitted in a downlink subframe configured forPRS transmission through higher layer signaling. When both a normalsubframe and a Multicast Broadcast Single Frequency Network (MBSFN)subframe are configured as positioning subframes, the OFDM symbols inthe MBSFN subframe configured for positioning need to use the sameCyclic Prefix (CP) as that of subframe #0. When only an MBSFN subframeis configured as a subframe for positioning, the symbols in thecorresponding MBSFN subframe configured to transmit a PRS need to use anextended CP.

The LTE PRS is transmitted through antenna port (AP) #6.

The LTE PRS may not be allocated to time/frequency resources to which aPhysical Broadcast Channel (PBCH), and a Primary Synchronization Signal(PSS)/Secondary Synchronization Signal (SSS) are allocated.

The LTE PRS is defined in an environment where a subcarrier space is 15kHz (i.e., Δf=15 kHz).

An LTE PRS sequence may be generated using a Gold-sequence-basedpseudo-random sequence generator as shown in Equation 1. Thepseudo-random sequence generator may be initialized to c_(init) at thestart of each OFDM symbol as shown in Equation 2.

$\begin{matrix}{\mspace{625mu}{\left\lbrack {{Equation}{\mspace{11mu}\;}1} \right\rbrack{{{r_{l,n_{s}}(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}},\mspace{79mu}{m = 0},1,\ldots\mspace{11mu},{{2N_{RB}^{\max,{DL}}} - 1}}}} & \; \\{\mspace{619mu}{\left\lbrack {{Equation}{\mspace{11mu}\;}2} \right\rbrack{c_{init} = {{2^{10} \cdot \left( {{7 \cdot \left( {n_{s} + 1} \right)} + l + 1} \right) \cdot \left( {{2 \cdot N_{ID}^{cell}} + 1} \right)} + {2 \cdot N_{ID}^{cell}} + N_{CP}}}\mspace{79mu}{N_{CP} = \left\{ \begin{matrix}1 & {{for}\mspace{14mu}{normal}\mspace{14mu}{CP}} \\0 & {{for}\mspace{14mu}{extended}\mspace{14mu}{CP}}\end{matrix} \right.}}} & \;\end{matrix}$

In Equation 1, l denotes a symbol index, n_(s) denotes a slot index, andN_(RB) ^(max,DL) denotes the maximum number of downlink resource blocks.In Equation 2, N_(ID) ^(cell) denotes a physical layer cell identity. Asshown in Equation 1, the LTE PRS is always generated based on themaximum number of downlink resource blocks (N_(RB) ^(max,DL)), althoughthe location and the size of a resource block to which the LTE PRS isactually mapped may vary.

In a downlink subframe configured for LTE PRS transmission, the LTE PRSsequence may be mapped to an RE, wherein the location of the RE may bedetermined based on Equation 3 in the case of a normal CP, or may bedetermined based on Equation 4 in the case of an extended CP.

$\begin{matrix}{{a_{k,l}^{(p)} = {r_{l,n_{s}}\left( m^{\prime} \right)}}{k = {{6\left( {m + N_{RB}^{DL} - N_{RB}^{PRS}} \right)} + {\left( {6 - l + v_{shift}} \right){mod}\; 6}}}{l = \left\{ {{{\begin{matrix}{3,5,6} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = 0} \\{1,2,3,5,6} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = {1\mspace{14mu}{and}}} \\\; & \left( {1\mspace{14mu}{or}\mspace{14mu} 2\mspace{14mu}{PBCH}\mspace{14mu}{antenna}\mspace{14mu}{ports}} \right) \\{2,3,5,6} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = {1\mspace{14mu}{and}}} \\\; & \left( {4\mspace{14mu}{PBCH}\mspace{14mu}{antenna}\mspace{14mu}{ports}} \right)\end{matrix}m} = 0},1,\ldots\mspace{11mu},{{{2 \cdot N_{RB}^{PRS}} - {1m^{\prime}}} = {m + N_{RB}^{\max,{DL}} - N_{RB}^{PRS}}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack \\{{a_{k,l}^{(p)} = {r_{l,n_{s}}\left( m^{\prime} \right)}}{k = {{6\left( {m + N_{RB}^{DL} - N_{RB}^{PRS}} \right)} + {\left( {5 - l + v_{shift}} \right){mod}\; 6}}}{l = \left\{ {{{\begin{matrix}{4,5} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = 0} \\{1,2,4,5} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = {1\mspace{14mu}{and}}} \\\; & \left( {1\mspace{14mu}{or}\mspace{14mu} 2\mspace{14mu}{PBCH}\mspace{14mu}{antenna}\mspace{14mu}{ports}} \right) \\{2,4,5} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = {1\mspace{14mu}{and}}} \\\; & \left( {4\mspace{14mu}{PBCH}\mspace{14mu}{antenna}\mspace{14mu}{ports}} \right)\end{matrix}m} = 0},1,\ldots\mspace{11mu},{{{2 \cdot N_{RB}^{PRS}} - {1m^{\prime}}} = {m + N_{RB}^{\max,{DL}} - N_{RB}^{PRS}}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack \\{v_{shift} = {N_{ID}^{cell}{mod}\; 6}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$

In Equations 3 and 4, the reference signal sequence r_(l,n) _(s) (m′)from Equation 1 may be mapped to a complex-valued modulation symbola_(k,l) ^((p)) which is used as a reference signal for an antenna portP. Here, k denotes a subcarrier index, N_(RB) ^(DL) denotes a downlinkbandwidth configuration (e.g., the number of RBs allocated for adownlink), N_(RB) ^(PRS) denotes an LTE PRS bandwidth configured by ahigher layer, and v_(shift) denotes a cell-specific frequency deviationvalue as shown in Equation 5. In Equations 3 and 4, m′ indicates that aPRB for an LTE PRS is located in a frequency region that corresponds tothe center of a bandwidth corresponding to the maximum number ofdownlink resource blocks. That is, out of the sequence generated basedon the maximum number of downlink resource blocks according to Equation1, only a sequence that corresponds to the location of a PRB to whichthe LTE PRS is mapped is actually mapped to an RE according to Equation3 and 4.

FIGS. 12 and 13 are diagrams illustrating an RE pattern in which an LTEPRS is mapped to a single resource block pair.

FIG. 12 illustrates examples of the location of an RE to which an LTEPRS is mapped when the number of PBCH antenna ports is 1 or 2 and thenumber of PBCH antenna ports is 4 in the case of the normal CP.

FIG. 13 illustrates examples of the location of an RE to which an LTEPRS is mapped when the number of PBCH antenna ports is 1 or 2 and thenumber of PBCH antenna ports is 4 in the case of the extended CP.

Next, a subframe configuration associated with an LTE PRS will bedescribed.

A cell-specific subframe configuration period T_(PRS) and an offsetΔ_(PRS) for LTE PRS transmission may be set according to Table 3provided below. A T_(PRS) and the Δ_(PRS) corresponding to the value ofan I_(PRS) provided through higher layer signaling may be determinedbased on Table 3. Accordingly, an LTE PRS transmission subframe isdetermined by a period T_(PRS) based on a subframe that is Δ_(PRS)distant from a subframe corresponding to System Frame Number (SFN) 0.Here, the LTE PRS may be transmitted on N_(PRS) consecutive downlinksubframes from the subframe determined by T_(PRS) and Δ_(PRS), and thevalue of N_(PRS) may be provided to a UE through higher layer signaling.That is, each LTE PRS positioning occasion may include N_(PRS)consecutive downlink subframes.

TABLE 3 PRS configuration PRS PRS subframe Index periodicity offsetI_(PRS) T_(PRS) (subframes) Δ_(PRS) (subframes)  0-159 160 I_(PRS)160-479 320 I_(PRS) − 160  480-1119 640 I_(PRS) − 480 1120-2399 1280 I_(PRS) − 1120 2400-4095 Reserved

Table 4 illustrates an example of higher layer signaling associated withan LTE PRS configuration.

TABLE 4 -- ASN1START PRS-Info ::= SEQUENCE { prs-Bandwidth ENUMERATED {n6, n15, n25, n50, n75, 100, . . . }, prs-ConfigurationIndex INTEGER(0..4095), numDL-Frames ENUMERATED {sf-1, sf-2, sf-4, sf-6, . . . }, . .. , prs-MutingInfo-r9  CHOICE {  po2-r9       BIT STRING (SIZE(2)), po4-r9       BIT STRING (SIZE(4)),  po8-r9       BIT STRING (SIZE(8)), po16-r9    BIT STRING (SIZE(16)),  . . . }

An information element in Table 4 may be referred to as PRS-Info, andmay provide information associated with an LTE PRS configuration in acell.

LTE PRS configuration information may include configuration informationof an LTE PRS (e.g., an LTE PRS for the Observed Time Difference OfArrival (OTDOA)) for a single reference serving cell from an LTEpositioning protocol (LPP) layer, that is, a location server. The LTEPRS configuration information may be provided to a UE via an eNB.

The LTE PRS configuration information may include the parameters shownin Table 4. Particularly, a PRS bandwidth (PRS-Bandwidth) is a valuewhich corresponds to a bandwidth used for configuring an LTE PRS, and isexpressed as the number of PRBs. The value of a PRS configuration index(prs-ConfigurationIndex) may indicate the value of I_(PRS) as shown inTable 3, and a PRS period (T_(PRS)) and an offset value (Δ_(PRS)) may beset based thereon. The number of downlink subframes (numDL-Frames) mayindicate the number of consecutive subframes (N_(PRS)) in which an LTEPRS is transmitted. PRS muting information provides informationassociated with the PRS muting configuration of a cell, is counted usingan LTE PRS positioning occasion as a unit, and is indicated in bitmapform having a period of T_(REP). When a bit is 0, LTE PRS transmissionis not performed in all downlink subframes in the corresponding PRSpositioning occasion (i.e., the LTE PRS transmission is muted).

FIG. 14 is a diagram illustrating an Observed Time Difference Of Arrival(OTDOA).

OTDOA is a positioning scheme in which a communication satellitetransmits information to a terrestrial station in LTE. OTDOA is based onmeasuring arrival time differences of radio signals transmitted fromvarious locations. A plurality of cells transmits reference signals, anda UE may receive the same. Because the distances between the pluralityof cells and the UE are different, the arrival times when the UEreceives the reference signals transmitted from the plurality of cellsare different from each other. The time differences may be recorded bythe UE and may be transmitted to a network. The network combines thetime differences and the antenna location information of each cell tocalculate the location of the UE. At least three cells may be measuredby the UE, and the at least three cells may include a reference cell anda neighboring cell.

The difference in time between when the UE receives reference signalsfrom each of a pair of eNBs is defined as a Reference Signal TimeDifference (RSTD). The position measurement is based on measuring a TDOAof a predetermined reference signal, which is included in a downlinksignal and is received from other eNBs.

FIG. 15 is a diagram illustrating a control plane and a user plane of anLTE positioning protocol (LPP).

The positioning technology may be defined by an Enhanced Cell ID(E-CID), Observed Time Difference of Arrival (OTDOA), a GlobalNavigation Satellite System (A-GNSS), and the like, which are capable ofsupporting positioning solutions for a control plane and a user plane atthe same time. An LTE network-based positioning function is managed byan Evolved-Serving Mobile Location Centre (E-SMLC)/Secure User PlaneLocation (SUPL) Location Platform (SLP).

Next, examples associated with an NB-PRS will be described.

First, the definition of an NB-PRS and a positioning operation based onan LTE PRS and an NB-PRS will be described.

The NB-PRS is defined only for a subcarrier space of 15 kHz (i.e., Δf=15kHz).

The NB-PRS may be transmitted only in a downlink subframe configured forNB-PRS transmission (hereinafter, an NB-PRS transmission subframe)through higher layer signaling. Detailed examples associated with theconfiguration of NB-PRS transmission subframes will be described later.

An eNB operating in NB-IoT does not configure an MBSFN subframe for a UEoperating in NB-IoT (hereinafter an NB UE), and thus, the NB UE mayoperate without information associated with an MBSFN subframe even in anin-band operation mode. When the NB UE is defined to support only anormal CP, the NB UE may operate in a subframe configured as an NB-PRStransmission subframe by always assuming that the normal CP is applied,irrespective of the existence of an MBSFN subframe that the NB eNB isaware of (i.e., that the NB UE is not aware of). In a guard-bandoperation mode or an out-band operation mode, an MBSFN subframe does notexist, and thus the NB UE may operate without information associatedwith the MBSFN subframe.

The NB eNB may be capable of supporting both a normal LTE UE and an NBUE (i.e., a UE in the LTE in-band and guard-band operation mode).

It is assumed that the NB UE supports only an NB-IoT function.Therefore, it is assumed that the NB UE may not be aware of alloperations including cell-specific information and the UE-specificinformation of normal LTE UEs. Therefore, to report the cell-specificinformation and the UE-specific information to the NB UE, NB-IoTsignaling may be used separately.

Next, the definition of an antenna port of an NB-PRS and its newsignaling scheme will be described.

An antenna port of an NB-PRS may be the same as the antenna port of anLTE PRS (i.e., antenna port index 6), or may be independent from theantenna port of the LTE PRS. The configuration of the NB-PRS antennaport (the configuration indicating whether an NB-PRS antenna port is thesame as an LTE PRS antenna port) may be provided to the NB UE throughhigher layer signaling, or may be determined in advance as a fixed valueso that the UE may know in advance without separate signaling.

When an NB-PRS is configured to be transmitted through the same antennaport as that of an LTE PRS, through higher layer signaling, the NB UEmay use both the NB-PRS and the LTE PRS (e.g., may use both the NB-PRSand the LTE PRS for generating positioning information (e.g., RSTD)).When the configuration indicates that the NB-PRS and the LTE PRS havethe same antenna port, the channel information estimated based on anNB-PRS of a neighboring RE and the channel information estimated basedon an LTE PRS of another RE may be used for channel estimation of an RE.That is, the performance of channel estimation may be increased bycombining channel information estimated by different types of referencesignals, and thus, the positioning performance may be increased.

For example, when the NB-PRS and the LTE PRS use the same antenna port,the NB UE may use both the channel information estimated using theNB-PRS and the channel information estimated using the LTE PRS togenerate positioning information (e.g., RSTD) in a subframe where anNB-PRS occasion and an LTE PRS occasion overlap according to theconfigurations of the NB-PRS occasion and the LTE PRS occasion.Alternatively, the NB UE may generate positioning information estimatedby assuming an NB-PRS as an LTE PRS. In the subframe where the occasionsoverlap, the NB UE may need to be aware of the LTE PRS sequence andpattern information in advance to receive an LTE PRS. The informationmay be set in advance or may be provided by an NB eNB.

When an antenna port, which is different and independent from theantenna port of an LTE PRS, is configured for an NB-PRS through higherlayer signaling, the NB UE may generate positioning information (e.g.,RSTD) using only the NB-PRS without using the LTE PRS.

Alternatively, when higher layer signaling associated with theconfiguration of an NB-PRS antenna port is not provided to the UE, theNB UE may assume that the NB-PRS antenna port is independent from thatof an LTE PRS, and generates positioning information (e.g., RSTD) usingonly the NB-PRS without using the LTE PRS.

Additionally or alternatively, a base station may configure the antennaport of an NB-PRS to be the same as or different from the antenna portof an LTE Cell-specific Reference Signal (CRS) (i.e., antenna port index0, 1, 2, or 3). The antenna port configuration may be performed throughhigher layer signaling.

For example, when an NB-PRS is configured to be transmitted through thesame antenna port as that of an LTE CRS through higher layer signaling,the NB UE may use the LTE CRS in all subframes in which an NB-PRS isreceived, because the LTE CRS is transmitted in all subframes.Therefore, the NB UE may use channel information estimated using anNB-PRS and channel information estimated using an LTE CRS to generatepositioning information (e.g., RSTD).

Additionally or alternatively, higher layer signaling may configure theantenna port of an NB-PRS to be the same as or independent from theantenna port of an LTE Discovery Reference Signal (DRS).

For example, when an NB-PRS is configured to be transmitted through thesame antenna port as that of an LTE DRS, through higher layer signaling,the LTE DRS may be transmitted in all subframes configured in advancethrough higher layer signaling. When the NB UE also receives an LTE DRSin a subframe in which an NB-PRS is received, the NB UE may use the LTEDRS to generate positioning information. Therefore, the NB UE may usechannel information estimated using the NB-PRS and channel informationestimated using the LTE DRS to generate positioning information (e.g.,RSTD). Here, the LTE DRS is a reference signal, which is used fordiscovering an accessible cell that provides sufficient receptionquality out of a plurality of small cells through a smaller amount ofpower consumed in a small cell environment. The LTE DRS is a referencesignal transmitted by small cell eNBs in a relatively long period (e.g.,a DRS occasion period configuration). The LTE DRS may be configured witha CRS, a PSS/SSS, and, if configured, a CSI-RS. For example, a singleDRS occasion is formed of a plurality of downlink subframes (e.g., 5subframes); a CRS, a PSS/SSS, and a CSI-RS may be transmitted in some orall of the downlink subframes. Therefore, in the same manner as theCRS/PRS, an indication that enables a DRS and an NB-PRS to have the sameantenna port may be provided to the UE through network signaling andthus, the positioning quality may be improved.

Additionally or alternatively, higher layer signaling may configure anantenna port that is the same as or independent from an antenna port ofan NPSS or an NSSS, which is used for purpose of synchronization in anNB-IoT system, as an antenna port of an NB-PRS.

One example is the case in which an NB UE is configured through higherlayer signaling (e.g., LPP layer or RRC layer) such that an NB-PRS istransmitted using the same antenna port as that of an NPSS or an NSSS.In this case, when the NB UE simultaneously receives an NPSS or NSSS ina subframe in which an NB-PRS is also received, the NB UE may use theNPSS or NSSS together with the NB-PRS to generate positioninginformation. Here, an NPSS will be transmitted in subframe #5 based on aperiod of 10 ms in a single radio frame, and an NSSS will be transmittedin subframe #9 based on a period of 20 ms in a single radio frame, andthus, the NPSS or the NSSS may overlap or may be adjacent to a subframeand a time domain where the NB-PRS will be transmitted. Therefore, whenthe configuration indicates that the NB-PRS and the NPSS or NSSS areusing the same antenna port, it means that both the channel informationestimated based on an NB-PRS of a neighboring RE and the channelinformation estimated based on an NPSS or NSSS of another RE may be usedfor channel estimation of an RE. That is, the performance of channelestimation may be increased by combining channel information estimatedby different types of reference signals, and thus, positioningperformance may be improved.

Additionally or alternatively, an antenna port that is the same as orindependent from an antenna port of a Narrowband Reference Signal (NRS),which is used for purpose of decoding a Narrowband Physical DownlinkShared Channel (NPDSCH) in an NB-IoT system, may be configured as anantenna port of an NB-PRS through higher layer signaling. Upon receivingthe higher layer signaling, a UE may assume that NRS port #0 isconfigured as an antenna port which is the same as that of the NB-PRS.Conversely, directly configuring a predetermined NRS antenna port as anantenna port that is the same as that of an NB-PRS for a UE is allowedthrough additional higher layer signaling.

For example, when it is configured, through higher layer signaling, thatan NB-PRS and an NRS are transmitted using the same antenna, theconfigured NRS antenna port may be used by a UE in a subframe in whichan NPDSCH is transmitted, and thus, this may not overlap a subframe inwhich an NB-PRS is transmitted. Therefore, a UE for which an NB-PRS andan NRS are configured to be transmitted in the same antenna port throughhigher layer signaling, may improve the reliability of positioninginformation by securing an NB-PRS transmission subframe and an NPDSCHtransmission subframe with an NRS to be performed contiguously from theperspective of time.

An NB-PRS sequence may be generated based on a PRB index correspondingto a center value of the total number of PRBs that an NRS assumes.

Therefore, the NB-PRS sequence may be generated based on the abovedescribed assumption, irrespective of a PRB through which an NB-PRS isto be transmitted, in the same manner as an NRS.

Higher layer configuration information associated with the antenna portof an NB-PRS may included in a Master Information block-Narrow Band(MIB-NB) and may be provided to UEs through a Narrow band PBCH (NPBCH),or may be included in a System Information Block (SIB) and may beprovided to UEs through a Narrow band PDSCH, or may be provided to UEsthrough dedicated RRC signaling or LPP signaling.

Hereinafter, the operations of an NB UE for receiving an NB-PRS and anLTE PRS will be described.

First, the case of the in-band operation mode will be described.

In addition to the configuration associated with the AP of an NB-PRS asdescribed above, the NB eNB may perform configuration such that NB-PRStransmission overlaps LTE PRS transmission in the time resource, thefrequency resource, or the time-frequency resources. The NB eNB mayconfigure LTE PRS and NB-PRS transmission resources based on a decreasein LTE PRS/NB-PRS overhead in a system or cell, more flexible LTEPRS/NB-PRS occasion, an LTE PRS/NB-PRS transmission subframe, an LTEPRS/NB-PRS PRB pair configuration, efficiency of utilizing frequencyresources, and the like.

FIG. 16 is a diagram illustrating an example of a first PRS transmissionresource and a second PRS transmission resource.

In the example shown in FIG. 16, a first PRS (e.g., NB-PRS) transmissionRB (or PRB) and a second PRS (e.g., LTE PRS) transmission RBs (or PRBs)may overlap in the time domain and the frequency domain.

In short, sequence generation and a mapping pattern for NB-PRStransmission may be different from sequence generation and a mappingpattern for LTE PRS transmission. In this instance, to support reversecompatibility associated with an LTE PRS, an NB UE may receive an NB-PRSin a PRB and a subframe in which both NB-PRS transmission and LTE PRStransmission are configured (i.e., where an NB-PRS and an LTE PRSoverlap), based on the sequence and the mapping pattern of the LTE PRS.For example, in a PRB (first PRS RB of FIG. 16) and a subframe in whichboth NB-PRS transmission and LTE PRS transmission overlap as shown inFIG. 16, an NB eNB may apply the sequence and the mapping pattern of anLTE PRS to an NB-PRS, and may transmit the same to the NB UE. Also,although different sequence generation and a different mapping patternare applied to an NB-PRS in another PRB and subframe where an NB-PRSdoes not overlap the LTE PRS, the sequence generation and a mappingpattern that are the same as that of an LTE PRS may be applied to theNB-PRS in a PRB (first PRS RB of FIG. 16) and a subframe in which theNB-PRS and the LTE PRS overlap. That is, although it is an NB-PRSsubframe, an eNB may transmit an LTE PRS instead, in a PRB and asubframe where the NB-PRS and the LTE PRS overlap. This may enable LTEUEs to maintain reverse compatibility. Accordingly, the NB UE maygenerate positioning information (e.g., RSTD) based on an LTE PRSinstead of an NB-PRS in a PRB and a subframe where the NB-PRS and theLTE PRS overlap (i.e., assuming an LTE PRS as an NB-PRS). The examplemay be applied to the case in which the antenna port of an LTE PRS isthe same as the antenna port of an NB-PRS, and to the case in which theyare independent from each other.

In particular, although an NB UE is not aware of system informationincluding cell-specific information and UE-specific information fornormal LTE UEs, if the NB UE receives information indicating whether anLTE Cell ID and an NB-IoT Cell ID are identical, LTE CRS sequenceinformation (including PRB index information (i.e., information forrecognizing a sequence in a predetermined PRB out of an LTE CRS sequencemapped to the entire band)), and the like through an NPBCH (or MIB-NB),and if the NB UE obtains an NB-IoT Cell ID through a Narrow band SSS(NSSS), the NB UE may expect that an LTE-PRS based on LTE-PRS sequencegeneration and a mapping pattern on the basis of the above describedinformation is received when an NB-PRS transmission resource and anLTE-PRS transmission resource overlap.

Table 5 provided below shows an example of the configuration of anMIB-NB information element.

TABLE 5 -- ASN1START MasterInformationBlock-NB :: = SEQUENCE { systemFrameNumber-MSB-r13 BIT STRING (SIZE (4)), hyperSFN-LSB-r13     BIT STRING (SIZE (2)), schedulingInfoSIB1-r13  INTEGER (0..15)), systemInfoValueTag-r13  INTEGER (0..31)),  ab-Enabled-r13      BOOLEAN channelRasterOffset-NB-r13  operationModeInfo-r13  CHOICE {  inband-SamePCI-r13    Inband-SamePCI-NB-r13  inband-DifferenctPCI-r13 Inband-DifferentPCI-NB-r13,  guardband-r13       Guardband-NB-r13  standalone-r13      Standalone-NB-r13  },  Spare          BIT STRING(SIZE (11)) }

In Table 5, systemFrameNumber-MSB-r13 denotes a field indicating an SFN.hyperSFN-LSB-r13 denotes a field indicating two Least Significant Bits(LSB) of HyperSFN. schedulingInfoSIB1-r13 denotes a field indicatingscheduling information of SIB1. systemInfoValueTag-r13 denotes a fieldindicating common information of SIBs excluding an MIB and SIB4/16.ab-Enabled-r13 denotes a field indicating that access barring is appliedwhen the value is TRUE. channelRasterOffset-NB-r13 denotes a fieldincluding offset information between an LTE channel raster and an NB-IoTcentral frequency. NB-IoT uses an LTE channel raster that appears foreach 100 kHz in an in-band mode that utilizes an LTE frequency band;thus, offset information associated with a frequency interval betweenthe LTE channel raster and with the central frequency of an PRB (orcarrier) where the NB-IoT is operated may be required.

Also, the operationModeInfo-r13 field may selectively include one out ofthe four modes, inband-SamePCI, inband-DifferenctPCI, guardband, andstandalone. Here, the inband-SamePCI-r13 field corresponds to an in-bandoperation mode having the same Physical Cell ID (PCID) as that of LTE,and may provide CRS sequence information (including PRB indexinformation) so that an LTE CRS is utilized. Also, theinband-DifferenctPCI-r13 field corresponds to an in-band operation modehaving a PCID different from that of LTE, and may additionally providethe number of LTE CRS APs and raster offset information. Also, theguardband-r13 and standalone-r13 fields indicate a guard-band operationmode and a standalone operation mode, respectively.

Here, PRB index indication information for providing LTE CRS sequenceinformation may be reused to obtain LTE PRS sequence information (i.e.,indicating the location of a PRB where an LTE PRS is transmitted in theentire system band). Accordingly, although an NB UE may not be directlyaware of the configuration information associated with an LTE PRS(sequence generation, a mapping pattern, a frequency location, atransmission subframe configuration, and the like), the NB UE may inferthe LTE PRS sequence information from other information as describedabove, and may receive the LTE PRS in an NB-PRS occasion.

Also, as described in FIG. 12, the NB UE may infer an LTE PRS patternthat is different based on the number of PBCH antenna ports (i.e., thenumber of CRS antenna ports), and may receive an LTE PRS. When theNB-IoT Cell ID is the same as the LTE Cell ID, the number of PBCHantenna ports may be signaled by an eNB, or the UE may assume that thenumber of PBCH antenna ports is the same as that of an Narrow BandReference Signal (NB-RS). Essentially, the NB UE determines the numberof NB-RS antenna ports in a process of receiving an NPBCH, and thus, theNB UE may assume that the determined number of NB-RS antenna ports isthe same as the number of LTE PBCH antenna ports. When the NB-IoT CellID is different from the LTE Cell ID, the number of LTE PBCH antennaports may be indicated by an NPBCH as shown in Table 5. The NB-RS istransmitted together with downlink channels, such as an NPBCH, anNPDCCH, an NPDSCH, and the like in an NB-IoT system, to demodulate thecorresponding channels.

When the NB-IoT Cell ID is different from the LTE Cell ID, LTE Cell IDinformation may be additionally provided to the NB UE, and may be usedfor determining an LTE PRS sequence. The NB UE only knows that the CellID value is different from that of LTE but does not know the accuratevalue of an LTE PCID, and thus, additional LTE Cell ID information needsto be provided to determine the LTE PRS sequence information. Theadditional information may be provided to the NB UE through higher layersignaling (e.g., LPP layer signaling).

Additionally, on the assumption that the NB UE is capable of receivingboth an NB-PRS and an LTE PRS, the NB UE may generate positioninginformation (e.g., RSTD) based on channel information estimated usingboth the NB-PRS and the LTE PRS even when an NB-PRS transmissionsubframe or a PRB does not overlap an LTE PRS transmission subframe or aPRB. For example, when the NB UE operates in an in-band operation mode,and an NB-PRS occasion and an LTE PRS occasion do not overlap, channelinformation estimated by different PRSs in different subframes may becombined. To this end, the configuration that enables the antennainformation of an NB-PRS and an LTE PRS to be the same may beeffectively used. In particular, the calculation of an RSTD uses channelstate information estimated successively in one or more configuredsubframes, and thus, the accuracy of positioning information of the NBUE may be improved when different PRSs in different subframes arecombined.

Subsequently, the sequence of an NB-PRS may be generated based onEquation 1 and Equation 2. Here, it is defined that NB-IoT supports onlythe normal CP, and thus, the case of the extended CP of Equation 2 maynot be considered. However, examples may not be limited thereto, and mayinclude the case in which the NB-IoT supports the extended CP.

An RE mapping pattern in an RB pair in a subframe of an NB-PRS may bedetermined based on Equation 3 and Equation 5. Here, N^(PRS) _(RB)denotes the bandwidth of an LTE PRS. In the case of an NB-PRS, only onePRB is used. N^(PRS) _(RB) in Equation 3 is replaced with 1, and it isdefined that m=0, 1 and m′=m+N^(max,DL) _(RB)−1. Equation 6 summarizesthis below. RE mapping patterns (e.g., FIGS. 17A, 17B, 18A, 18B, 19A,19B, and 20) that may be applied to a guard-band operation mode or astandalone operation mode may use only a single PRB in the same manneras an in-band operation mode, but may have different time-frequencylocations from that of the RE mapping pattern of the in-band operationmode. Therefore, the NB-PRS patterns of the guard-band operation mode orthe standalone operation mode may be expressed to be similar to Equation6, but may be expressed by setting different values for k (frequency REindex) and l (OFDM symbol index) in Equation 6.

$\begin{matrix}{{a_{k,l}^{(p)} = {r_{l,n_{s}}\left( m^{\prime} \right)}}{k = {{6\left( {m + N_{RB}^{DL} - 1} \right)} + {\left( {6 - l + v_{shift}} \right){mod}\; 6}}}{l = \left\{ {{{\begin{matrix}{3,5,6} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = 0} \\{1,2,3,5,6} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = {1\mspace{14mu}{and}}} \\\; & \left( {1\mspace{14mu}{or}\mspace{14mu} 2\mspace{14mu}{PBCH}\mspace{14mu}{antenna}\mspace{14mu}{ports}} \right) \\{2,3,5,6} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = {1\mspace{14mu}{and}}} \\\; & \left( {4\mspace{14mu}{PBCH}\mspace{14mu}{antenna}\mspace{14mu}{ports}} \right)\end{matrix}m} = 0},{{1m^{\prime}} = {m + N_{RB}^{\max,{DL}} - 1}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

Since it is defined that NB-IoT supports only the normal CP, the NB-PRSmapping pattern may not consider the case of the extended CP of Equation4. However, examples may not be limited thereto, and may include thecase in which the NB-IoT supports the extended CP. In this instance,N^(PRS) _(RB) of Equation 4 may be replaced with 1.

Here, in the NB-PRS sequence generation and mapping patterndetermination, N^(Cell) _(ID) from Equations 2 and 5 may be replacedwith N^(NCell) _(ID) which is the value of an NB-IoT Cell ID. When theNB eNB indicates that the LTE Cell ID and the NB-IoT Cell ID are thesame, N^(Cell) _(ID) and N^(NCell) _(ID) may be set to be the same.

FIGS. 17A, 17B, 18A, 18B, 19A, 19B, and 20 are diagrams illustrating anNB-PRS RE mapping pattern in a guard-band operation mode or a standaloneoperation mode.

NB-IoT is capable of operating in three operation modes, the in-band,the guard-band, and the stand-alone operations. Three operation modesmay be included in the MIB-NB information transferred by an NPBCH andmay be provided to all NB UEs in a cell based on a cell-specific scheme.

In the guard-band operation mode and in the standalone operation mode, alegacy LTE PRS pattern that is defined in a single subframe and a singlePRB (180 kHz) is not used as is; instead, a new NB-PRS pattern may beused. Unlike the in-band operation mode, an LTE control region and a CRStransmission do not exist in time-frequency resources where theguard-band operation mode or the standalone operation mode is applied.That is, the LTE PRS pattern is designed based on the assumption that acontrol region and a CRS always exist, and thus, an LTE PRS is notallocated in the control region and a CRS transmission OFDM symbol.

The NB-PRS pattern of the guard-band operation mode and the standaloneoperation mode may consider the allocation of a new NB-PRS pattern to anew OFDM symbol region in the LTE PRS pattern. Also, in the NB-PRSpattern, a frequency reuse factor 6 (i.e., v_shift=NB_PCID mod 6) ismaintained; a delay spread generated in an indoor channel environment(i.e., rich-multipath scenario) may further increase a side-lobe valueduring the estimation of a Time of Arrival (TOA) of a UE, and thus, moreuniform NB-PRS allocation may be considered in view of the frequencydomain. Information associated with whether the NB_PCID is the same asan LTE_PCID is provided through higher layer signaling (e.g., MIB-NB).When the NB_PCID is different from the LTE_PCID, a value provided by anNSSS is used as the value of the NB_PCID and the number of CRS ports maybe provided by the MIB-NB as LTE CRS information. Here, although theLTE_PCID and the NB_PCID are different from each other, the NB eNB mayensure that the value of v_shift indicated by the LTE_PCID is the sameas the value of v_shift indicated by the NB_PCID derived from the NSSS.

FIG. 21 is a diagram illustrating other examples of a first PRStransmission resource and a second PRS transmission resource.

In the examples shown in FIGS. 17A, 17B, 18A, and 18B, a first PRS(e.g., NB-PRS) transmission RB (or PRB) uses the same resource (e.g.,PRB) as that of the second PRS (e.g., LTE PRS) transmission RBs (orPRBs) in the frequency domain, but uses different resources (e.g.,subframes) in the time domain. Here, the example in FIG. 21 illustratesthat an NB-PRS transmission subframe and an LTE PRS subframe arediscontiguous in the time domain, and the example in FIG. 22 illustratesthat they are contiguous.

As described above, an NB UE may be provided with information associatedwith an LTE PRS occasion and a related configuration in addition toconfiguration information associated with an NB-PRS, from an NB eNBthrough higher layer signaling. The examples shown in FIGS. 16 and 21assume that an NB-PRS configuration and an LTE PRS configuration areindependently provided from an LPP layer.

In the example shown in FIG. 22, a configuration associated with anNB-PRS occasion (e.g., an NB-PRS period and an offset) may be providedto an NB UE by being associated with a configuration associated with anLTE PRS occasion (e.g., an LTE PRS period and an offset, which have beendescribed with reference to Table 3) so that the NB-PRS occasion and theLTE PRS occasion are always contiguously allocated.

For example, in the example shown in FIG. 22, an offset (SecondPRS_Offset) and a period (Second PRS_Periodicity) for configuring an LTEPRS occasion may be provided to a UE. In addition, configurationinformation associated with the NB-PRS occasion may be provided in theform of the NB-PRS offset value based on the LTE PRS occasion.

For example, the NB-PRS offset may be defined in the form of thedifference between the start point of the LTE PRS occasion and the startof the NB-PRS occasion, that is, the form of First PRS_Offset1 in theexample shown in FIG. 22. In this instance, when the value of FirstPRS_Offset1 is given as the number of consecutive downlink subframes ofthe LTE PRS (the value of N_(PRS) in the descriptions of Table 3), thatis, the value corresponding to the second PRS downlink subframes in theexample shown in FIG. 22, the LTE PRS occasion and the NB-PRS occasionmay be configured to be contiguous.

Alternatively, the NB-PRS offset may be defined in the form of adifference between the end point of the LTE PRS occasion and the startof the NB-PRS occasion, that is, the form of First PRS_Offset2 in theexample shown in FIG. 22. In this instance, when the value of FirstPRS_Offset2 is 0, the LTE PRS occasion and the NB-PRS occasion may beconfigured to be contiguous.

Alternatively, it may be assumed that the offset value of the LTE PRSoccasion and the NB-PRS occasion is determined in advance to be 0, and aUE is aware that the value is 0 even though the value is not separatelysignaled to the UE. This may indicate that the LTE PRS occasion and theNB-PRS occasion are always allocated to be contiguous.

When the LTE PRS occasion and the NB-PRS occasion are contiguouslyallocated, as described above, an NB UE may use a larger amount ofreception energy to generate a single piece of positioning information(e.g., an RSTD measurement sample value), thereby generating higherquality positioning information. Therefore, when the NB-PRS occasion andthe LTE PRS occasion are contiguously allocated, an RSTD measurementsample may be generated in a single occasion including both the NB-PRSoccasion and the LTE PRS occasion. Subsequently, this may be consideredto be a single sample value for reporting an RSTD.

As described above, when the NB UE is provided with informationassociated with an LTE PRS configuration in addition to NB-PRSconfiguration information, an NB UE may perform a positioning operationusing both an NB-PRS and an LTE PRS, thereby generating high-qualitypositioning information.

Therefore, regardless of whether an NB-PRS occasion and an LTE PRSoccasion overlap or not, and regardless of whether an NB-PRStransmission PRB and an LTE PRS transmission PRB overlap or not, when anNB UE is provided with LTE PRS configuration information in addition toNB-PRS configuration information, the NB UE may generate positioninginformation (e.g., RSTD) using an LTE PRS in the LTE PRS occasion, andmay generate positioning information using an NB-PRS in the NB-PRSoccasion.

Although the above description has been provided by mainly assuming anin-band operation mode, examples may not be limited thereto, and otherexamples may be applied to the guard-band operation mode or thestandalone operation mode. For example, the NB UE may generatepositioning information using all of an NB-PRS transmitted in theguard-band operation mode, an LTE PRS transmitted on a carrier band thatthe corresponding guard-band belongs to, and/or an LTE PRS transmittedon another carrier (i.e., combining channel information estimated basedon the NB-PRS and channel information estimated based on the LTE PRS).In the same manner, the NB UE may generate positioning information usingall of an NB-PRS transmitted in the standalone operation mode, an LTEPRS transmitted on another carrier (i.e., combining channel informationestimated based on the NB-PRS and channel information estimated based onthe LTE PRS). Accordingly, the NB UE may further improve positioningquality when compared to the case of using only an NB-PRS.

Here, an inter-carrier positioning operation (e.g., measuring an RSTD)may be applied when a plurality of carriers are configured for a UE(i.e., when data transmission/reception between an eNB and a UE isperformed on a plurality of carriers).

Next, examples associated with a NB-PRS transmission subframeconfiguration will be described. Subsequently, examples associated withan operation when an NB-PRS subframe overlaps another NB channel,signal, or configuration will be described. Hereinafter, it is assumedthat an NB-PRS transmission subframe configuration operates on all validsubframes. A subframe that may be considered an NB-PRS transmissionsubframe in an NB-IoT system will be described later. Therefore, it isassumed that the following subframe configuration is applied to onlyvalid subframes, and a valid subframe may be indicated based on a validsubframe configuration for NB-IoT. When the configuration does notexist, subframes remaining after excluding a subframe in which an NPBCH,an SIB1, an NPSS, or an NSSS is transmitted may be considered validsubframes. The following proposed NB-PRS occasion and subframeconfiguration may be applied based on the above-described configurationof the valid subframes.

NB-PRS transmission subframes may be configured in consideration ofNB-IoT requirements, such as extended coverage (e.g., MCL 164 dBm),reduced complexity, a low price, an improved battery life (about 10years), and the like, as described in Table 1.

In NB-PRS transmission subframes, a unit including one or moreconsecutive downlink subframes may be expressed as an NB-PRS occasion.Next, the example associated with the number of consecutive downlinksubframes forming the NB-PRS occasion will be described.

As described with reference to Table 3 and Table 4, the LTE PRS occasionmay be formed of 1, 2, 4, or 6 (i.e., N_(PRS) or numDL-Frames)consecutive downlink subframes. The number of consecutive subframes forthe LTE PRS occasion may be defined considering the fact that an LTE PRSuses 6, 15, 25, 50, 75, 100 PRBs (i.e., prs-Bandwidth), . . . , or thelike.

An NB IoT system operates in essentially one single PRB (e.g., afrequency domain of 180 kHz bandwidth). Accordingly, even given powerboosting, the NB IoT system may consider allocating a larger number oftransmission subframes for an NB-PRS when compared to an LTE PRS, inorder to secure sufficient positioning performance in an indoor channelenvironment. That is, to enable the UE to obtain sufficient NB-PRSreception energy and to generate positioning information (e.g., RSTD), asufficiently large amount of time resources (i.e., subframes) may beallocated for NB-PRS transmission to compensate for frequency resources,which are limited to a single PRB.

Table 6 provided below shows candidates for the number of consecutivedownlink (DL) subframes (Num_DL_subframe) for an NB-PRS. Here, the valueof Num_DL_subframe denotes the number of one or more consecutivedownlink subframes forming a unit, which is referred to as an NB-PRStransmission window. For example, when an NB-PRS transmission window isthe size of a single radio frame, Num_DL_frame may indicate the numberof one or more consecutive downlink subframes. Each NB-PRS occasion maybe configured to correspond to a duration in which the NB-PRStransmission window is repeated R times.

Here, the set of the candidates for an R value may be defined as {1, 2,4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048 . . . }, and the R value maybe set to one of the candidates in the set. Alternatively, the R valuemay not be defined (e.g., it may be defined in advance that R=1, and theNB-PRS transmission window may not be defined), and a single NB-PRSoccasion may be indicated using only a Num_DL_subframe configuration.

Also, the values shown in Table 6 provided below may be candidate valuesfor Num_DL_subframe, and some of them may not be used.

TABLE 6 Num_DL_subframe Value Descriptions Option 1 {1, 2, 4, 6} Set tovalue equal to NPRS (or numDL-Frames of Table 4) of LTE PRSConfiguration of repetitive transmission of NB-PRS transmission windowis essential. Option 2 {12, 24, 36, 72, Configuration of repetitive 144,288, 576, transmission of NB-PRS 1152, 2304 . . . } transmission windowis allowed. Option 3 {8, 16, 32, 64, Configuration of repetitive 128,256, 512, transmission of NB-PRS 1024, 2048 . . . } transmission windowis allowed.

Here, predetermined subframes may be excluded from the consecutivedownlink subframes used for an NB-PRS. The predetermined subframes maybe subframes in which downlink transmission associated with some or allof at least an NPBCH, an SIB1, System Information(s) (SI(s)), an NPSS,an NSSS, paging, a DL gap, random access-related transmission, an MBSFN,and a NarrowBand Single Cell Point-To-Multi-point transmission(NB-SC-PTM), exists. Here, three schemes may be considered for excludingthe predetermined subframes.

A first exclusion scheme counts subframes remaining after excluding thepredetermined subframes as consecutive DL subframes (i.e.,Num_DL_subframe subframes), and thus, it is indicated that an NB-PRStransmission may not be performed in the predetermined subframes.Particularly, the first scheme may be applied to some or all of a DL gapand a subframe in which an NPBCH, an SIB1, an NPSS, or an NSSS transmitssystem information and a synchronization signal.

A second exclusion scheme counts consecutive DL subframes (i.e.,Num_DL_subframe subframes) including the predetermined subframes;however, NB-PRS transmission is not actually performed in thepredetermined subframes, or counts and performs NB-PRS transmission(i.e., the case in which NB-PRS transmission takes precedence).

A third exclusion scheme does not count subframes, and N_(PRS)transmission is delayed until a subsequent valid subframe. That is, thethird scheme excludes a duration that includes the predeterminedsubframes and delays NB-PRS transmission to a duration whenNum_DL_subframe consecutive subframes exist (i.e., the case in which thenumber of consecutive valid subframes for NB-PRS transmission isNum_DL_subframe).

The detailed examples thereof will be described below regarding theoperation when an NB-PRS subframe overlaps another NB channel, signal,or configuration. Therefore, consecutive subframes used herein may notbe consecutive if the predetermined subframes are included as subframesor counted in determining the consecutiveness. However, the consecutivesubframes also includes the subframes remaining after eliminating thepredetermined subframes are arranged consecutively. Also, an NBtransmission subframe configuration may be cell-specific configuration(e.g., common to UEs) or UE-specific configuration.

Next, provided are examples associated with configuring NB-PRStransmission subframes using the number of consecutive downlinksubframes (Num_DL_subframe) which form a single NB-PRS transmissionwindow and associated with the number of times (R) that the NB-PRStransmission window is repeated.

An NB eNB may provide Num_DL_subframe and an R value to an NB UE.Accordingly, the UE may determine that an NB-PRS occasion is formed ofsubframes of which the number corresponds to a product ofNum_DL_subframe and the R value, wherein Num_DL_subframe is the numberof consecutive downlink subframes, and the R value is the number ofrepetitive transmissions.

The Num_DL_subframe and the R value may be defined as cell-specificinformation, and may be provided to all NB UEs in a cell by the NB eNB.Alternatively, the Num_DL_subframe and the R value may be defined asUE-specific information to prevent the UE's power consumption. Also, theNum_DL_subframe and the R value may be defined independently for eachcell. For example, different Num_DL_subframe and different R values maybe set for a reference cell and for a neighboring cell.

FIG. 23 is a diagram illustrating an example of configuring an NB-PRSoccasion.

A first PRS (e.g., NB-PRS) occasion configuration and a repetitivetransmission configuration will be described with reference to theexample shown in FIG. 23.

A period and an offset for an NB-PRS occasion may be defined by twoschemes.

The first scheme configures a NB-PRS occasion for each period (FirstPRS_Periodicity#1 of FIG. 23) from a subframe indicated by an NB-PRSoffset (First PRS_Offset of FIG. 23) based on SFN=0 and slot=0.According to the second scheme, a first NB-PRS occasion (First PRSoccasion #0 of FIG. 23) starts from a subframe indicated by an NB-PRSoffset (First PRS_Offset of FIG. 23) based on SFN=0 and slot=0, and asubsequent NB-PRS occasion (First PRS occasion #1 of FIG. 23) startsfrom a point that is a period (First PRS_Periodicity#2 of FIG. 23)distant from a point where the immediately previous NB-PRS occasionends. The second scheme may minimize overlap between NB-PRS occasionswhen compared to the first scheme.

Each NB-PRS occasion may be configured based on the number ofconsecutive downlink subframes (Num_DL_subframe), which form in a singleNB-PRS transmission window, and the number of repetitive transmissions(R), as described above. The example shown in FIG. 23 assumes thatDL_subframes corresponds to the number of one or more consecutivedownlink subframes that belong to a single NB-PRS transmission window,and R (R_cell of FIG. 23) given as cell-specific information is 4. Thatis, a single NB-PRS occasion may be configured by repeating atransmission window including DL_subframes subframes four times.

FIG. 24 is a diagram illustrating another example of configuring anNB-PRS occasion.

The configuration of a first PRS (e.g., NB-PRS) occasion will bedescribed from the perspective of an eNB (or cell) and from theperspective of an UE, with reference to the example shown in FIG. 24.

The example in FIG. 24 assumes that Num_DL_subframe, which is aparameter indicating the number of DL_subframes consecutive downlinksubframes (e.g., subframes included in an NB-PRS transmission window),is set to be a cell-specific parameter. In the case of R, which is aparameter indicating the number of times that an NB-PRS transmissionwindow is repeated, it is assumed that a cell-specific value and aUE-specific value coexist. For example, as shown in FIG. 24, R_cell=4,which is set as a cell-specific value; R_ue1=2, which is set as a firstUE (UE1)-specific value; and R_ue2=4, which is set as a second UE(UE2)-specific value.

In FIG. 24, subframes when DL_subframes consecutive downlink subframes(e.g., NB-PRS transmission window) are repeated R_cell times, may be afirst PRS (e.g., NB-PRS) occasion from the perspective of the cell. Thismay be repeatedly configured according to a predetermined offset andperiod (e.g., First PRS_Offset and First PRS_Periodicity#1 or FirstPRS_Periodicity#2). This may be the same as a first PRS (e.g., NB-PRS)occasion configured from the perspective of the second UE (UE2).Meanwhile, a first PRS (e.g., NB-PRS) occasion configured from theperspective of the first UE (UE1) may be formed by repeatingDL_subframes two times.

Additionally, the UE-specific NB-PRS configuration may be set to bedifferent for each cell. For example, a UE1-specific NB-PRSconfiguration may be set in detail a, DL_subframes #0 subframes and R=2for a reference cell (or serving cell), DL_subframes #1 subframes andR=4 for neighboring cell #1, and DL_subframes #3 subframes and R=3 forneighboring cell #2.

NB UEs may have a normal coverage or an extreme coverage based on achannel environment, an application, a UE capability, and the like. Inthe example shown in FIG. 24, a first UE (UE1) may be a UE within anormal coverage, and a second UE (UE2) may be a UE belonging to anextreme coverage. An NB-PRS occasion configuration including a largenumber of repetitive transmissions may be needed for an NB UE thatexists in a poor channel environment of an extreme coverage in view of acell. An NB-PRS occasion for NB UEs within the normal coverage may notneed to include a large number of repetitive transmissions; thus,supporting early termination of the NB-PRS occasion may be considered tominimize the power consumption of the NB UEs. That is, through theconfiguration associated with the number of repetitive transmissions (R)appropriate for a coverage an NB UE exists within and the number ofconsecutive DL_subframes (Num_DL_subframe), the battery power consumedfor receiving an NB-PRS and generating positioning information (e.g.,RSTD) may be minimized.

From the perspective of the first UE (UE1) within the normal coverage,cell-specific NB-PRS occasion configuration information (e.g., R_cell)may be transparent. The information that is transparent to a UEindicates that the UE is incapable of detecting the information. Forexample, in a subframe duration, which corresponds to the NB-PRSoccasion of the second UE but does not correspond to the NB-PRS occasionof the first UE, an eNB may perform control through scheduling,configuring a DL gap, configuring valid subframes, or the like withrespect to the first UE, so that the second UE receives an NB-PRS andperforms a positioning operation but the first UE does not perform apositioning operation. Alternatively, when cell-specific NB-PRS occasionconfiguration information (e.g., R_cell) is not transparent to the firstUE, UE-specific configuration information (e.g., R_ue1) may be set tooverride the cell-specific configuration information.

FIG. 25 is a diagram illustrating another example of configuring anNB-PRS occasion.

A scheme will be described for dynamically setting a UE-specificconfiguration associated with a first PRS (e.g., NB-PRS) occasion, withreference to the example in FIG. 25.

The example shown in FIG. 25 is similar to the example in FIG. 24.However, in the example shown in FIG. 25, a configuration associatedwith each first PRS occasion (e.g., NB-PRS occasion) (e.g., aconfiguration associated with DL_subframes and R) may be dynamicallysignaled to each UE. That is, dynamic signaling may be provided beforeevery NB-PRS occasion, or may be provided at set intervals in aplurality of NB-PRS occasions. Also, the dynamically signaled NB-PRSoccasion configuration information may not be limited to a UE-specific Rparameter, and the number of consecutive DL subframes may be dynamicallychanged.

In addition to the NB-PRS subframe configuration, dynamic NB-PRSconfiguration information, such as an NB-PRS muting pattern, powerallocation (including power boosting information), and the like, may bedynamically provided to each cell and/or each UE through a locationserver (LPP layer) according to a channel environment where acorresponding UE is located or according to the capability of acorresponding UE. The dynamic information may be controlled by thelocation server to avoid interference to the positioning measurementresults of other UEs located in a serving cell or a neighboring cell.Hereinafter, although the descriptions will be provided from theperspective of the dynamical configuration of NB-PRS subframes, thelocation server may perform signaling for each UE/each cell, so as tocontrol the above described other dynamic configuration information(NB-PRS muting pattern, power allocation, and the like) to bedynamically optimized based on a cell ID (cell) and the channelenvironment and location of a UE.

In the example shown in FIG. 25, in the case of a first UE (UE1),although the value of the UE-specific repeat count parameter (R_ue1) ina first first-PRS-occasion (UE1_First PRS occasion #0) is set to 2, thevalue in a second first-PRS-occasion (UE1_First PRS occasion #1) may bedynamically changed to 3. Also, in the case of a second UE (UE2),although the value of the UE-specific repeat count parameter (R_ue2) ina first first-PRS-occasion (UE2_First PRS occasion #0) is set to 4, thevalue in a second first-PRS-occasion (UE2_First PRS occasion #1) may bedynamically changed to 2.

The example in FIG. 25 increases a signaling overhead when compared tothe example in FIG. 24. However, the example in FIG. 25 may support amore flexible NB-PRS transmission/reception operation, reduced batteryenergy consumption, and more effective resource utilization.

The dynamic NB-PRS configuration may be reported to the location serverby each eNB, and an NB-PRS configuration between associated (orneighboring) eNBs may be coordinated and may be dynamically provided toUEs (i.e., the NB-PRS configuration of a UE may be reconfigured).

Next, provided are examples associated with an operation performed whenan NB-PRS subframe overlaps another NB channel, signal, orconfiguration.

NB downlink transmission may include the transmission of an NPBCH, anNPSS, an NSSS, an NPDSCH, a Narrow band PDCCH (NPDCCH), an SIB(s),paging, a random access-related transmission (e.g., Random AccessResponse (RAR) that responds to a random access preamble), a messageindicating the retransmission of an uplink transmission (message 3(Msg3)) scheduled by an RAR, a contention resolution message (message 4(Msg4) or the like)), or an NSC-PTM, in addition to NB-PRS transmission.Also, a downlink gap (DL gap) (i.e., a gap configured to enable anotherUE to use some of a long period of time when an NPDCCH or an NPDSCH fora predetermined NB UE is transmitted during the long period of time) anda valid subframe configuration may be additionally provided for flexibleNPDCCH and NPDSCH transmission and scheduling.

The NB channels and signals are repeatedly transmitted using a largeamount of time resources, and thus may have a high probability ofoverlapping (colliding with) NB-PRS transmission. Also, NB-PRStransmission may be restricted by an MBSFN configuration. Also, an NBeNB may intentionally schedule or configure an NB-PRS subframe tooverlap another NB channel, signal, or configuration, for effectivelyutilizing resources and effectively controlling operations of a UE.

Next, provided are examples associated with an operation performed whenan NB-PRS subframe overlaps another NB channel, signal, orconfiguration.

First, a UE may be configured to not expect NB-PRS transmission on aresource where a channel or signal having a higher priority than that ofan NB-PRS is transmitted. For example, an NB-PRS may not be allocated totime-frequency resources where an NPBCH, SIB1, NPSS, or NSSS isallocated. Therefore, the UE may determine not to transmit an NB-PRS ona subframe in which an NPBCH, SIB1, NPSS, or NSSS is transmitted. Forexample, when a subframe configured as an NB-PRS transmission subframeoverlaps a subframe in which an NPBCH, SIB1, NPSS, or NSSS istransmitted, the UE may attempt the reception of the NPBCH, SIB1, NPSS,or NSSS, and may not try (or expect) to receive an NB-PRS. That is, asubframe in which at least the channel and signaling is transmitted maynot be counted in determining consecutive NB-PRS subframes.

Next, an example of determining an NB-PRS transmission subframeaccording to a valid subframe configuration will be described. In thissection, the valid subframe configuration may be for downlinktransmission or for an NB-PRS-dedicated valid subframe configuration.

Downlink subframes corresponding to an NB-PRS occasion may be determinedbased on the valid subframe configuration. That is, the examples of theNB-PRS subframe configuration, which have been described with referenceto Table 6 and FIGS. 23-25, may be applied to subframes that areindicated as or determined to be valid subframes. That is, the examplesassociated with the above described NB-PRS subframe configuration may beapplied to the subframes other than invalid subframes.

FIG. 26 is a diagram illustrating an example of a valid subframe for anNB-PRS.

As illustrated in FIG. 26, an NB-PRS configuration may be applied basedon a valid subframe configuration, excluding a subframe in which anNPBCH, SIB1, NPSS, or NSSS is transmitted in a single NB-PRS occasion.That is, a consecutive-NB-PRS-subframe configuration may be only appliedto valid subframes.

As another example, an NB-PRS subframe configuration may be appliedindependently, irrespective of a valid subframe configuration. That is,a subframe that is not configured as a valid subframe may also beconfigured for NB-PRS transmission through the NB-PRS subframeconfiguration. The configuration may provide a degree of freedom whichis independent from a valid subframe configuration, thereby enabling theeffective management among a plurality of cells.

Table 7 provided below illustrates an example of higher layer signalingfor a valid subframe configuration for an NB UE. For example, aninformation element including the fields listed in Table 7 may bereferred to as DL-Bitmap-NB, which may be used for defining the set ofNB-IoT downlink subframes for downlink transmission. When an NB UE doesnot receive information associated with a valid subframe configuration(e.g., a DL-Bitmap-NB information element) from an NB eNB, the NB UE mayassume that the downlink subframes remaining (after excluding subframesin which an NPBCH, SIBL NPSS, or NSSS is transmitted) are validsubframes.

TABLE 7 -- ASN1START DL-Bitmap-NB-r13 ::= CHOICE{ subframePattern10-r13  BIT STRING (SIZE (10)) subframePattern40-r13  BIT STRING (SIZE (40)) } -- ASN1STOP

In Table 7, subframePattern10 is bitmap information indicating an NB-IoTdownlink subframe configuration over a time interval of 10 ms, and maybe defined for an in-band operation mode, a guard-band operation mode,and a standalone operation mode. Also, subframePattern40 is bitmapinformation indicating an NB-IoT downlink subframe configuration over atime interval of 40 ms, and may be defined for an in-band operationmode. A first/the leftmost bit of the bitmap corresponds to subframe #0that satisfies SFN mod x=0 in a radio frame; x corresponds to a valueobtained by dividing a bit string by 10. Therefore, the configurationmay be repeatedly applied by a period of 10 ms or 40 ms. “0” in thebitmap indicates that a corresponding subframe is invalid for downlinktransmission, and “1” indicates that the corresponding subframe is validfor downlink transmission.

Next, the operation performed when an NPDCCH or NPDSCH transmissionsubframe overlaps an NB-PRS transmission subframe will be described.

A search space (SS) for an NPDCCH may be configured, by higher layersignaling, to be periodically provided to each UE according to aconfiguration created by an eNB. The SS for an NPDCCH may indicate acandidate resource region in which an NPDCCH may be transmitted. An NBUE may monitor and attempt to detect the NPDCCH from the configured SSbased on a blind decoding scheme. A maximum repetitive transmissionconfiguration associated with an NPDCCH during a single period may beprovided by higher layer signaling (e.g., RRC signaling), and arepetitive transmission value to be applied to the UE may be dynamicallyindicated by DCI signaling in the maximum repetitive configuration.

Table 8 illustrates an example of higher layer signaling for an NPDCCHconfiguration. In this example, an information element including thefields listed in Table 8 may be referred to asNPDCCH-ConfigDedicated-NB, which may define subframes and resourceblocks for monitoring an NPDCCH.

TABLE 8 -- ASN1START NPDCCH-ConfigDedicated-NB-r13 ::=   SEQUENCE { npdcch-NumRepetitions-r13 ENUMERATED {r1, r2, r4,     r8, r16, r32,r64,     r128, r256, r512,     r1024, r2048, spare4,     spare3, spare2,    spare1},  npdcch-StartSF-USS-r13 ENUMERATED {v1dot5, v2,     v4, v8,v16, v32,     v48, v64},  npdcch-Offset-USS-r13    ENUMERATED {zero,oneEighth,   oneFourth, threeEighth} } -- ASN1STOP

The npdcch-NumRepetitions field in Table 8 indicates a maximumrepetitive transmission configuration value (1, 2, 4, 7, 16, 32, 64,128, 256, 512, 1024, 2048, . . . ) for an NPDCCH during a single period.Also, the npdcch-StartSF-USS field indicates the start subframe of aUE-specific search space (USS), and indicates the UE-specific searchspace which beings from a subframe indicated by a predetermined offsetvalue (npdcch-Offste-USS field) based on the start subframe.

The size and location of the SS for receiving an NPDCCH may bedetermined based on an aggregation level (AL), the maximum number ofrepetitive transmissions, and an SS start subframe configuration. WhenNPDCCHs of various UEs are repeatedly transmitted, the NPDCCHs of theUEs are transmitted by being distinguished in different time resources,that is, by using the Time Division Multiplexing (TDM) scheme. An NPDCCHand an NPDSCH for a single UE may both be transmitted based on a TDMscheme. As described above, in a limited frequency resource (e.g., asingle PRB), NPDCCHs for a plurality of UEs and an NPDCCH and an NPDSCHfor a single UE are transmitted through the TDM scheme. Therefore, inthe time domain, an NB-PRS transmission subframe, which issemi-statically configured by a higher layer, may have a highprobability of overlapping an NPDCCH or NPDSCH transmission, which isdynamically scheduled based on whether traffic associated with a UEexists.

As described above, the operation performed when an NPDCCH SS, therepetitive transmission of an NPDCCH, and/or the repetitive transmissionof an NPDSCH overlaps an NB-PRS, will be defined as follows.

When the subframe belonging to an NB-PRS occasion overlaps an NPDCCH SS(i.e., a UE-specific search space, that is, a resource region in whichan NPDCCH for providing the unicast NPDSCH scheduling informationassociated with a predetermined UE may be transmitted), an NB UE mayexpect to receive an NB-PRS.

Alternatively, the NB UE may not actually expect to receive an NB-PRS ina subframe in which an NPDCCH/NPDSCH is repeatedly transmitted for apredetermined purpose (e.g., some or all of paging, SI, SC-PTM, andrandom access-related transmission). Instead, the NB UE may expect toreceive an NB-PRS in a subframe where an NPDCCH/NPDSCH has beenconfigured to be transmitted for the maximum number of repetitivetransmissions, but the repetitive transmission of the NPDCCH/NPDSCH doesnot actually occur.

FIG. 27 is a diagram illustrating an NB-PRS transmission operation whenan NB-PRS transmission subframe overlaps an NPDCCH transmissionsubframe.

The example in FIG. 27 assumes that an NB UE successfully receives anNPDCCH in a subframe ahead of the subframes belonging to an NB-PRSoccasion, but subframes in which the transmission of the correspondingNPDCCH is expected (i.e., subframes determined based on the maximumnumber of an NPDCCH's repetitive transmissions) overlap the subframesbelonging to the NB-PRS occasion.

For example, when a value corresponding to the maximum number ofrepetitive transmissions of an NPDCCH (R_max) is 8, an SS fortransmitting an NPDCCH may be configured over a maximum of 8 subframes.Within a range of the maximum value, an NB eNB may signal the R valuecorresponding to the number of times that an NPDCCH is repeatedlytransmitted according to a channel environment of an NB UE, to the UEthrough DCI. The example in FIG. 27 assumes that, for example, R=4.Therefore, when the NB UE successfully detects only a single NPDCCHwhile an NPDCCH is repeatedly transmitted four times, the NB UE maydetermine the end point of the repetitive transmission of an NPDCCH.That is, in the example shown in FIG. 27, when the NB UE successfullydetects an NPDCCH in one of the downlink subframes corresponding to R=4DCI signaling, it may be determined that the repetitive transmission ofthe NPDCCH is to be terminated at a fourth DL subframe in a durationindicated by R_max=8. Accordingly, the NB UE may not need to performmonitoring for an NPDCCH in a subframe subsequent to the subframe wherethe repetitive transmission of an NPDCCH is terminated. The NB eNBterminates scheduling early with respect to the single NB UE, and mayattempt to perform scheduling with respect to another UE, thus improvingoverall system performance.

In a situation when the subframe(s) belonging to an NB-PRS occasionoverlap the NPDCCH or NPDSCH transmission subframe(s), a UE may excludeany subframe in which the reception of an NB-PRS is not expected (i.e.,a subframe in which the transmission of an NPDCCH is actually repeated(a subframe corresponding to R=4 in FIG. 27)).

According to a first exclusion scheme, the NB UE counts consecutivedownlink subframes used for an NB-PRS by excluding a subframe in whichNB-PRS transmission is not expected, and then determines which subframesbelong to an NB-PRS occasion (particularly, an NB-PRS transmissionwindow). That is, the NB-PRS occasion may be determined by counting onlythe subframes remaining after excluding the subframe(s) in which NB-PRStransmission is not expected. Accordingly, as shown in the example inFIG. 27, it may be expressed that the start point of the subframesbelonging to the NB-PRS occasion is postponed for a period of timecorresponding to the subframes in which the reception of an NB-PRS isnot expected.

According to a second exclusion scheme, the NB UE may exclude a subframein which transmission of an NB-PRS is not expected from the consecutivedownlink subframes used for an NB-PRS. That is, the NB UE may firstdetermine the set of subframes belonging to an NB-PRS occasion accordingto a repeat count (R) parameter and may next determine the number ofdownlink subframes for an NB-PRS configured by the NB eNB. The NB UE maythen attempt to receive an NB-PRS in only the subframe(s) remainingafter excluding a subframe in which the transmission of an NB-PRS is notexpected from the set. In the example in FIG. 27, the first two DLsubframes out of the 8 DL subframes indicated for an NB-PRS occasion(First PRS occasion #0 of FIG. 27) overlaps an NPDCCH repetitivetransmission subframe, and thus, the reception of an NB-PRS is notexpected. Accordingly, it is determined that the NB-PRS occasion isformed of the 6 DL subframes remaining after excluding the correspondingsubframes.

The NB eNB transmits an NPDCCH in a subframe in which an NPDCCH isrepeatedly transmitted (a subframe indicated by R=4 DCI Signaling inFIG. 27), and transmits an NB-PRS from a subsequent subframe.

When a subframe in which an NPDSCH scheduled through a previouslyreceived NPDCCH is transmitted overlaps subframes belonging to an NB-PRSoccasion, the NB UE may expect to receive an NPDSCH, and the NB UE maynot expect to receive an NB-PRS.

Additionally, in a subframe in which an NPDSCH is repeatedly transmittedand an NPDCCH SS for transmission/reception related to at least some orall of paging, SI, SC-PTM, and random access-related transmission isrepeatedly transmitted, the NB UE may not expect to receive an NB-PRS.This may secure the UE to receive system information which is moreimportant than the position measurement of the UE, and thus, the cellconnection of the UE may be continuously maintained and secured.

For example, in the case of a single transmission block (TB) fortransmission of an SI (excluding SIB1), when the NB-PRS occasionoverlaps the SIB transmission, the NB eNB may not transmit an NB-PRS onthe overlapping subframe, and the NB UE may not expect to receive theNB-PRS on the corresponding subframe.

Also, when an NPDCCH subframe for transmitting and receiving paging orrandom access-related transmission (e.g., an RAR, an Msg3 retransmissionmessage, an Msg4, or the like) overlaps the subframes included in theNB-PRS occasion, the NB UE may not expect to receive an NB-PRS on thecorresponding subframe.

FIG. 28 is a diagram illustrating an NB-PRS subframe that overlaps an NBchannel and a downlink gap.

The example shown in FIG. 28 illustrates the case in which an NB-PRSoccasion configured for a UE overlaps a downlink gap (DL gap) that isconfigured to allow the transmission and reception of an NPDCCH, NPDSCH,and/or Narrowband PUSCH (NPUSCH) of another UE during a UE's NBtransmission (First PRS occasion of FIG. 28).

In this instance, when the NB-PRS occasion configured for the NB UEoverlaps a downlink gap for another UE, the NB UE may not expect toreceive an NB-PRS. An NB-PRS subframe is not counted as an NB-PRSsubframe in the overlapping interval, and the transmission may bepostponed to a subsequent valid NB-PRS subframe that does not overlap.

Next, a new downlink gap defined in an NB-PRS occasion will bedescribed.

The downlink gap considered in the examples described above is for anNPDCCH and an NPDSCH. In addition, a new downlink gap may be configuredin an NB-PRS occasion. This may be referred to as NB-PRS_DL Gap. Theadditional NB-PRS_DL Gap may be employed to secure the transmissionoccasion of another UE that requires urgent data scheduling, in themiddle of an NB-PRS occasion that allows repetitive transmission onsubframes.

NB-PRS_DL Gap, which is configured in the NB-PRS occasion, may beconfigured for an NB UE through higher layer signaling. When a thresholdvalue is set for a maximum NPDCCH repetitive transmission configurationthat implies a coverage environment, and a maximum NPDCCH repetitivetransmission configuration exists that exceeds the correspondingthreshold value, NB-PRS_DL Gap may be configured. When the maximumNPDCCH repetitive transmission configuration is less than or equal tothe corresponding threshold value, NB-PRS_DL Gap may not be configured.

As described in one or more examples, when a subframe in which the NB UEdoes not expect NB-PRS transmission is determined, the NB UE maydetermine a NB-PRS transmission subframe by applying a first exclusionscheme or a second exclusion scheme.

According to the first exclusion scheme, when a subframe in which the NBUE does not expect NB-PRS transmission is determined, the NB UE firstcounts consecutive downlink subframes used for an NB-PRS by excludingthe determined subframe, and then determines subframes belonging to theNB-PRS occasion (particularly, an NB-PRS transmission window). That is,the NB-PRS occasion may be determined by counting the subframesremaining after excluding the subframe in which NB-PRS transmission isnot expected.

According to the second exclusion scheme, when a subframe in which theNB UE does not expect NB-PRS transmission is determined, the NB UE mayexclude the determined subframe from the consecutive downlink subframesused for an NB-PRS. That is, the NB UE may determine the set ofsubframes belonging to the NB-PRS occasion according to both a repeatcount (R) parameter and the number of downlink subframes for an NB-PRSconfigured by the NB eNB. Then the NB UE may attempt to receive anNB-PRS in the subframe(s) remaining after excluding from the set asubframe in which the transmission of an NB-PRS is not expected.

In this instance, a threshold value associated with the number ofsubframes in which an NB-PRS is not received may be set for the NB UE.Accordingly, when the number of NB-PRS subframes in which the NB UE doesnot receive an NB-PRS (or does not expect to receive an NB-PRS) in asingle NB-PRS occasion exceeds a predetermined threshold value, the NBUE determines that the value calculated based on NB-PRSs received in thecorresponding NB-PRS occasion is invalid. Therefore, the value may notbe used for generating positioning information.

FIG. 29 is a flowchart illustrating first PRS transmission and receptionoperations.

In operation S2910, an eNB determines the configuration of a first PRS(e.g., NB-PRS) to be transmitted to a UE. The configuration of the firstPRS may include an RE pattern in a first PRS transmission subframe, afirst PRS sequence, a first PRS transmission PRB configuration, a firstPRS transmission subframe configuration, a first PRS antenna portconfiguration, and the like, as described in one or more examples. Inoperation S2910, the eNB determines the configuration of a second PRS(e.g., LTE PRS) to be transmitted to the UE. The configuration of theLTE PRS may include an RE pattern in a second PRS transmission subframe,a second PRS sequence, a second PRS transmission PRB configuration, asecond PRS transmission subframe configuration, a second PRS antennaport configuration, and the like.

In operation S2920, the eNB provides the UE with the first PRSconfiguration-related information and the second PRSconfiguration-related information, which are determined in operationS2910. The first PRS configuration-related information and the secondPRS configuration-related information may be provided to the UE throughseparate signaling. The first PRS configuration-related information andthe second PRS configuration-related information may be provided to theUE at the same time, or may be provided to the user at different pointsin time. The parts of the first PRS configuration-related informationmay be provided through one or more signalings, and the parts of thesecond PRS configuration-related information may also be providedthrough one or more signaling.

In operation S2930, the eNB transmits a first PRS and a second PRS tothe UE. One or both of a time resource and a frequency resource in whichthe first PRS is transmitted may overlap one or both of a time resourceand a frequency resource in which the second PRS is transmitted.Alternatively, the first and second PRSs may be transmitted in differenttime-frequency resources (i.e., not overlapping time-frequencyresources). The UE may attempt to receive the first PRS and the secondPRS based on the first and second PRS configuration information receivedin operation S2920.

In operation S2940, the UE may generate positioning information (e.g.,information used for determining the location of the UE itself, such asan RSTD) using the first PRS received from the eNB, may generatepositioning information using the second PRS, or may generatepositioning information using both the first and second PRSs. When thetime-frequency resources in which the first PRS is transmitted overlapthe time-frequency resources in which the second PRS is transmitted, theUE may use only the second PRS in the overlapping time-frequencyresources to generate positioning information. When the time-frequencyresources in which the first PRS is transmitted do not overlap thetime-frequency resources in which the second PRS is transmitted, the UEmay use only the first PRS to generate positioning information, may useonly the second PRS to generate positioning information, or may use boththe first and second PRSs to generate positioning information.

In operation S2950, the UE transmits the positioning informationgenerated in operation S2940 to the eNB or to an NB-IoT server (orlocation server) via the eNB.

Although the above described illustrative methods are expressed as aseries of operations for ease of description, they may not limit theorder of operations executed, and the operations may be executed inparallel or in a different order. Also, one or more of the operationsdescribed above may be omitted in some implementations.

An NB UE may process a positioning reference signal by performing one ormore operations below. The NB UE receives positioning reference signal(PRS) configuration information, determine narrowband PRS (NB PRS)configuration information for the NB UE, the NB PRS configurationinformation comprising information of an NB PRS reference cell thatgenerates an NB PRS for the NB UE; and determine PRS configurationinformation for a UE, the UE being assigned to use a frequency bandunavailable for the NB UE, and the PRS configuration informationcomprising information of a PRS reference cell that generates a PRS forthe UE. The NB UE may generate, based on the NB PRS configurationinformation and the PRS configuration information, a reference signaltime difference (RSTD) measurement, and transmit the RSTD measurement.

The UE may be an LTE UE capable of processing a plurality of physicalresource blocks not available for the NB UE.

The NB UE may determine a first NB PRS mapped in one physical resourceblock (PRB) and transmitted from the NB PRS reference cell, anddetermine a portion of a first PRS mapped in the one PRB and transmittedfrom the PRS reference cell, wherein the first PRS mapped in a pluralityof PRBs. The RSTD measurement may be generated based on the first NB PRSand the portion of the first PRS.

The NB UE may determine a second NB PRS mapped in the one PRB andtransmitted from an NB PRS neighbor cell and determine a portion of asecond PRS mapped in the one PRB and transmitted from a PRS neighborcell, wherein the second PRS mapped in the plurality of PRBs. The NB UEmay calculate, based on a receipt time difference between the first NBPRS and the second NB PRS and between the portion of the first PRS andthe portion of the second PRS, a first RSTD.

The NB UE may determine a third NB PRS mapped in the one PRB andtransmitted from a second NB PRS neighbor cell and a portion of a thirdPRS mapped in the one PRB and transmitted from a second PRS neighborcell, wherein the third PRS mapped in the plurality of PRBs. The NB UEmay calculate, based on a receipt time difference between the first NBPRS and the third NB PRS and between the portion of the first PRS andthe portion of the third PRS, a second RSTD.

The RSTD measurement may be generated based on the first RSTD and thesecond RSTD.

The NB UE may be assigned to use a frequency band corresponding to onephysical resource block (PRB), and the UE is assigned to use a frequencyband corresponding to a plurality of PRBs, the plurality of PRBscomprising the one PRB.

A more advance NB UE may be assigned to use two PRBs or three PRBs orthe like. However, an NB UE is not capable of using all LTE frequencybands available for an LTE UE.

The NB UE may receive physical resource block (PRB) index indicating theone PRB and determine, based on the received PRB index, the NB PRSmapped in the one PRB and a portion of the PRS mapped in the one PRB.

The NB UE may receive, from the NB PRS reference cell, an NB PRS mappedin one physical resource block (PRB). The NB PRS may be configured to bemapped in a subframe in which narrowband physical broadcasting channel(NPBCH), narrowband primary synchronization signal (NPSS), narrowbandsecondary synchronization signal (NSSS), or System Information Blocktype 1 (SIB1).

An NB UE may determine NB positioning reference signal (PRS)configuration information for the NB UE, the NB PRS configurationinformation comprising information of an NB PRS reference cell thatgenerates an NB PRS for the NB UE, receive the NB PRS for the NB UE, andreceive a PRS for a UE, the UE being assigned to use a first frequencyband available for the NB UE and a second frequency band unavailable forthe NB UE. The NB UE may generate, based on the NB PRS and the PRS, areference signal time difference (RSTD) measurement and transmit theRSTD measurement.

The NB UE may determine the same antenna port of the NB UE to receivethe NB PRS and the PRS.

The PRS may be generated based on a Long-Term Evolution (LTE) protocol(including LTE-Advanced protocol). The first frequency band maycorrespond to one physical resource block (PRB) available for the NB UE,and the second frequency band may correspond to a plurality of PRBsunavailable for the NB UE.

The NB PRS configuration information may be received via a Long-TermEvolution Positioning Protocol (LPP) signaling layer.

Some portion of the NB PRS and some portion of the PRS mapped in thefirst frequency band are transmitted in the same subframe. Some portionof the NB PRS is transmitted in a subframe in which the PRS is nottransmitted.

The NB PRS configuration information may include a physical resourceblock (PRB) index that indicates the first frequency band in which theNB PRS and a portion of the PRS are mapped.

A network including a base station may process a PRS. The network maytransmit, to a narrow-band (NB) user equipment (UE), narrowband PRS (NBPRS) configuration information for the NB UE, the NB PRS configurationinformation comprising information of an NB PRS reference cell thatgenerates an NB PRS for the NB UE, and transmit, to the NB UE, PRSconfiguration information for a UE, the UE being assigned to use afrequency band unavailable for the NB UE, and the PRS configurationinformation comprising information of a PRS reference cell thatgenerates a PRS for the UE. The base station may transmit, to the NB UE,an NB PRS for the NB UE. The base station may transmit a PRS for a UE,the UE being assigned to use a first frequency band available for the NBUE and a second frequency band unavailable for the NB UE. Although thePRS is generally targeted for one or more UEs. A portion of the PRS maybe received and processed by one or more NB UEs. The network mayreceive, from the NB UE, a reference signal time difference (RSTD)measurement, the RSTD measurement being based on the NB PRS and the PRSassociated with the first frequency band.

The NB PRS and the PRS may be transmitted by using a same antenna portof the base station. The NB PRS configuration information and the PRSconfiguration information may be generated by an Evolved-Serving MobileLocation Centre (E-SMLC).

The NB PRS configuration information may include a number ofCell-specific Reference Signal (CRS) ports and an NB reference cell IDcorresponding to a reference cell ID of the base station.

The NB PRS configuration information may include a physical resourceblock (PRB) index that indicates the first frequency band in which theNB PRS and a portion of the PRS are mapped.

FIG. 30 is a diagram illustrating the configuration of a processor for awireless device.

The processor 210 of the eNB 200 may be configured to implement theoperations of an eNB described herein.

For example, the higher layer processing unit 211 of the processor 210of the eNB 200 may include a first-and-second-PRS configurationgenerating unit 3040 and a first-and-second-PRS configuration-relatedinformation generating unit 3050.

The first-and-second PRS configuration determining unit 3040 maydetermine an RE pattern in a first PRS transmission subframe, a firstPRS sequence, a first PRS transmission PRB configuration, a first PRStransmission subframe configuration, a first PRS antenna portconfiguration, and the like. The first-and-second PRS configurationdetermining unit may also determine an RE pattern in a second PRStransmission subframe, a second PRS sequence, a second PRS transmissionPRB configuration, a second PRS transmission subframe configuration, asecond PRS antenna port configuration, and the like. According to thefirst PRS configuration and second PRS configuration determined asdescribed above, the first-and-second-PRS configuration-relatedinformation generating unit 3050 may generate signaling information in aformat separately determined in advance for a first PRS and a secondPRS, and may transmit the same to a UE through the physical layerprocessing unit 212. For example, the first PRS configuration-relatedinformation and the second PRS configuration-related information may beprovided to the UE through separate signaling. Also, the first PRSconfiguration-related information and the second PRSconfiguration-related information may be provided to the UE at the sametime, or may be provided to the user at different points in time. Also,the parts of the first PRS configuration-related information may beprovided through one or more signaling operations, and the parts of thesecond PRS configuration-related information may also be providedthrough one or more signaling operations.

The physical layer processing unit 212 of the processor 210 of the eNB200 may include a first-and-second-PRS transmitting unit 3060. Thefirst-and-second-PRS transmitting unit 3060 may map the first PRS andthe second PRS onto physical resources respectively allocated theretoaccording to the first PRS configuration and the second PRSconfiguration, and may transmit the same to the UE 100. For example, oneor both of a time resource and a frequency resource in which the firstPRS is transmitted may overlap one or both of a time resource and afrequency resource in which the second PRS is transmitted.Alternatively, the first and second PRSs may be transmitted in differenttime-frequency resources (i.e., not overlapping time-frequencyresources).

The processor 110 of the UE 100 may be configured to implement theoperations of a UE described herein.

For example, the higher layer processing unit 111 of the processor 110of the UE 100 may include a first-and-second-PRS configurationdetermining unit 3010 and a positioning information generating unit3020. The physical layer processing unit 112 of the processor 110 of theUE 100 may include a first-and-second-PRS receiving unit 3030.

The first-and-second-PRS configuration determining unit 3010 maydetermine an RE pattern in a transmission subframe, a sequence, atransmission PRB configuration, a transmission subframe configuration,an antenna port configuration, and the like for each of a first PRS anda second PRS, based on first PRS configuration-related information andsecond PRS configuration-related information provided from the eNB 200.

The first-and-second-PRS receiving unit 3030 may receive a first PRS anda second PRS using physical resources based on the determined first PRSconfiguration and the second PRS configuration.

The positioning information generating unit 3020 may generatepositioning information based on one or more out of the received firstPRS and second PRS, and may transmit the same to an eNB or anetwork-side server through the physical layer processing unit 112.

The descriptions provided through one or more examples may be applied tothe operations of the UE 100 and the eNB, and repetitive descriptionswill be omitted.

Although various examples of the present disclosure have been describedfrom the perspective of the 3GPP LTE or LTE-A system, they may beapplied to other various mobile communication systems.

What is claimed is:
 1. A narrow-band (NB) wireless device comprising:one or more processors; and memory storing instructions that, whenexecuted by the one or more processors, cause the NB wireless device to:receive positioning reference signal (PRS) configuration information;determine narrowband PRS (NB PRS) configuration information for the NBwireless device, the NB PRS configuration information for the NBwireless device comprising information of an NB PRS reference cell thatgenerates an NB PRS for the NB wireless device; determine PRSconfiguration information for a wireless device, the wireless devicebeing assigned to use a frequency band unavailable for the NB wirelessdevice, and the PRS configuration information for the wireless devicecomprising information of a PRS reference cell that generates a PRS forthe wireless device; generate, based on the NB PRS configurationinformation for the NB wireless device and the PRS configurationinformation for the wireless device, a reference signal time difference(RSTD) measurement; and transmit the RSTD measurement.
 2. The NBwireless device of claim 1, wherein the instructions, when executed bythe one or more processors, cause the NB wireless device to: determine afirst NB PRS mapped in one physical resource block (PRB) and transmittedfrom the NB PRS reference cell; and determine a portion of a first PRSmapped in the one PRB and transmitted from the PRS reference cell,wherein the first PRS mapped in a plurality of PRBs, and wherein theRSTD measurement is generated based on the first NB PRS and the portionof the first PRS.
 3. The NB wireless device of claim 2, wherein theinstructions, when executed by the one or more processors, cause the NBwireless device to: determine a second NB PRS mapped in the one PRB andtransmitted from an NB PRS neighbor cell; determine a portion of asecond PRS mapped in the one PRB and transmitted from a PRS neighborcell, wherein the second PRS mapped in the plurality of PRBs; andcalculate, based on a receipt time difference between the first NB PRSand the second NB PRS and between the portion of the first PRS and theportion of the second PRS, a first RSTD.
 4. The NB wireless device ofclaim 3, wherein the instructions, when executed by the one or moreprocessors, cause the NB wireless device to: determine a third NB PRSmapped in the one PRB and transmitted from a second NB PRS neighborcell; determine a portion of a third PRS mapped in the one PRB andtransmitted from a second PRS neighbor cell, wherein the third PRSmapped in the plurality of PRBs; and calculate, based on a receipt timedifference between the first NB PRS and the third NB PRS and between theportion of the first PRS and the portion of the third PRS, a secondRSTD.
 5. The NB wireless device of claim 4, wherein the instructions,when executed by the one or more processors, cause the NB wirelessdevice to generate the RSTD measurement by: generating, based on thefirst RSTD and the second RSTD, the RSTD measurement.
 6. The NB wirelessdevice of claim 1, wherein the NB wireless device is assigned to use afrequency band corresponding to one physical resource block (PRB), andthe wireless device is assigned to use a frequency band corresponding toa plurality of PRBs, the plurality of PRBs comprising the one PRB. 7.The NB wireless device of claim 6, wherein the instructions, whenexecuted by the one or more processors, cause the NB wireless device to:receive physical resource block (PRB) index indicating the one PRB; anddetermine, based on the received PRB index, the NB PRS mapped in the onePRB and a portion of the PRS mapped in the one PRB.
 8. The NB wirelessdevice of claim 1, wherein the instructions, when executed by the one ormore processors, cause the NB wireless device to: receive, from the NBPRS reference cell, an NB PRS mapped in one physical resource block(PRB), wherein the NB PRS is configured to be mapped in a subframe inwhich narrowband physical broadcasting channel (NPBCH), narrowbandprimary synchronization signal (NPSS), narrowband secondarysynchronization signal (NSSS), or System Information Block type 1 (SIB1)is not allocated.
 9. A narrow-band (NB) wireless device comprising: oneor more processors; and memory storing instructions that, when executedby the one or more processors, cause the NB wireless device to:determine NB positioning reference signal (PRS) configurationinformation for the NB wireless device, the NB PRS configurationinformation comprising information of an NB PRS reference cell thatgenerates an NB PRS for the NB wireless device; receive the NB PRS forthe NB wireless device; receive a PRS for a wireless device, thewireless device being assigned to use a first frequency band availablefor the NB wireless device and a second frequency band unavailable forthe NB wireless device; generate, based on the NB PRS and the PRS, areference signal time difference (RSTD) measurement; and transmit theRSTD measurement.
 10. The NB wireless device of claim 9, wherein theinstructions, when executed by the one or more processors, cause the NBwireless device to: determine a same antenna port of the NB wirelessdevice to receive the NB PRS and the PRS.
 11. The NB wireless device ofclaim 9, wherein the PRS is generated based on a Long-Term Evolution(LTE) protocol, and wherein the first frequency band corresponds to onephysical resource block (PRB) available for the NB wireless device, andthe second frequency band corresponds to a plurality of PRBs unavailablefor the NB wireless device.
 12. The NB wireless device of claim 9,wherein the NB PRS configuration information is received via a Long-TermEvolution Positioning Protocol (LPP) signaling layer.
 13. The NBwireless device of claim 9, wherein a portion of the NB PRS and aportion of the PRS mapped in the first frequency band are transmitted ina subframe.
 14. The NB wireless device of claim 9, wherein a portion ofthe NB PRS is transmitted in a subframe in which the PRS is nottransmitted.
 15. The NB wireless device of claim 9, wherein the NB PRSconfiguration information comprises: a physical resource block (PRB)index that indicates the first frequency band in which the NB PRS and aportion of the PRS are mapped.
 16. One or more base stations comprising:one or more processors; and memory storing instructions that, whenexecuted by the one or more processors, cause the one or more basestations to: transmit, to a narrow-band (NB) wireless device, narrowbandPRS (NB PRS) configuration information for the NB wireless device, theNB PRS configuration information comprising information of an NB PRSreference cell that generates an NB PRS for the NB wireless device;transmit, to the NB wireless device, PRS configuration information for awireless device, the wireless device being assigned to use a frequencyband unavailable for the NB wireless device, and the PRS configurationinformation comprising information of a PRS reference cell thatgenerates a PRS for the wireless device; transmit, from a base stationto the NB wireless device, an NB PRS for the NB wireless device;transmit, from the base station, a PRS for a wireless device, thewireless device being assigned to use a first frequency band availablefor the NB wireless device and a second frequency band unavailable forthe NB wireless device; and receive, from the NB wireless device, areference signal time difference (RSTD) measurement, the RSTDmeasurement being based on the NB PRS and the PRS associated with thefirst frequency band.
 17. The one or more base stations of claim 16,wherein the NB PRS and the PRS are transmitted by using a same antennaport of the base station.
 18. The one or more base stations of claim 16,wherein the NB PRS configuration information and the PRS configurationinformation are generated by an Evolved-Serving Mobile Location Centre(E-SMLC).
 19. The one or more base stations of claim 16, wherein the NBPRS configuration information comprises: a number of Cell-specificReference Signal (CRS) ports; and an NB reference cell ID correspondingto a reference cell ID of the base station.
 20. The one or more basestations of claim 16, wherein the NB PRS configuration informationcomprises: a physical resource block (PRB) index that indicates thefirst frequency band in which the NB PRS and a portion of the PRS aremapped.